<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedBalanceSheets" xlink:href="agnc-20160331.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedBalanceSheetsParentheticals" xlink:href="agnc-20160331.xsd#ConsolidatedBalanceSheetsParentheticals" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:href="agnc-20160331.xsd#ConsolidatedStatementOfStockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="agnc-20160331.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:href="agnc-20160331.xsd#ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstruments" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstruments" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTables" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:href="agnc-20160331.xsd#DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DocumentAndEntityInformation" xlink:href="agnc-20160331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurements" xlink:href="agnc-20160331.xsd#FairValueMeasurements" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurementsDetails" xlink:href="agnc-20160331.xsd#FairValueMeasurementsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurementsTables" xlink:href="agnc-20160331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecurities" xlink:href="agnc-20160331.xsd#InvestmentSecurities" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesNarrativeDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesTables" xlink:href="agnc-20160331.xsd#InvestmentSecuritiesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/Organization" xlink:href="agnc-20160331.xsd#Organization" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/OrganizationDetails" xlink:href="agnc-20160331.xsd#OrganizationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssets" xlink:href="agnc-20160331.xsd#PledgedAssets" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsNarrativeDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsRepurchaseAgreementsWithCounterpartiesGreaterThanOrEqualTo5OfEquityAtRiskDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsRepurchaseAgreementsWithCounterpartiesGreaterThanOrEqualTo5OfEquityAtRiskDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:href="agnc-20160331.xsd#PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsTables" xlink:href="agnc-20160331.xsd#PledgedAssetsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebt" xlink:href="agnc-20160331.xsd#RepurchaseAgreementsAndOtherDebt" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtFederalHomeLoanBankAdvancesAndWeightedAverageInterestRatesDetails" xlink:href="agnc-20160331.xsd#RepurchaseAgreementsAndOtherDebtFederalHomeLoanBankAdvancesAndWeightedAverageInterestRatesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:href="agnc-20160331.xsd#RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:href="agnc-20160331.xsd#RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtTables" xlink:href="agnc-20160331.xsd#RepurchaseAgreementsAndOtherDebtTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquity" xlink:href="agnc-20160331.xsd#StockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:href="agnc-20160331.xsd#StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:href="agnc-20160331.xsd#StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityPreferredStockDetails" xlink:href="agnc-20160331.xsd#StockholdersEquityPreferredStockDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityTables" xlink:href="agnc-20160331.xsd#StockholdersEquityTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SubsequentEvent" xlink:href="agnc-20160331.xsd#SubsequentEvent" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SubsequentEventDetails" xlink:href="agnc-20160331.xsd#SubsequentEventDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="agnc-20160331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesAccountingPoliciesPolicies" xlink:href="agnc-20160331.xsd#SummaryOfSignificantAccountingPoliciesAccountingPoliciesPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="agnc-20160331.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesPolicy" xlink:href="agnc-20160331.xsd#SummaryOfSignificantAccountingPoliciesPolicy" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/UnauditedInterimConsolidatedFinancialStatements" xlink:href="agnc-20160331.xsd#UnauditedInterimConsolidatedFinancialStatements" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedBalanceSheetsParentheticals" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_F6A93F5B840A36508721816A7EB273FC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_StatementTable_F6A93F5B840A36508721816A7EB273FC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3619A18C82E6DD265F02816A7EB207AD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_F6A93F5B840A36508721816A7EB273FC" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3619A18C82E6DD265F02816A7EB207AD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3619A18C82E6DD265F02816A7EB207AD" xlink:to="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3619A18C82E6DD265F02816A7EB207AD" xlink:to="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaap_PreferredStockMember_6DE5482906AAE5531482816A7EB2E236" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:to="loc_us-gaap_PreferredStockMember_6DE5482906AAE5531482816A7EB2E236" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_FE034705F9A0F625851B816A7EBC1625" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:to="loc_us-gaap_CommonStockMember_FE034705F9A0F625851B816A7EBC1625" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_7B11D2E74320DBD92C17816A7EBC45E4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_7B11D2E74320DBD92C17816A7EBC45E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_D522A6FBE49FE35A7561816A7EBC00F1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:to="loc_us-gaap_RetainedEarningsMember_D522A6FBE49FE35A7561816A7EBC00F1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4AEA068F53214820FB6B816A7EBCCB5C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_49D20429FEE332A4E298816A7EB2C255" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4AEA068F53214820FB6B816A7EBCCB5C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_32460F4BF3C08184BAC1816A7EBCF0DB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_StockholdersEquity_32460F4BF3C08184BAC1816A7EBCF0DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_FE83053ECE49F905BF40816A7EBC6D6F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_FE83053ECE49F905BF40816A7EBC6D6F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_FB157440CABBBAE02247816A7EBCA33E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_FB157440CABBBAE02247816A7EBCA33E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_3F8CC3A09D0D41CA8BAA816A7EBCF972" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_NetIncomeLoss_3F8CC3A09D0D41CA8BAA816A7EBCF972" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_5C213AA35070C7369424816A7EBCF6AA" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_5C213AA35070C7369424816A7EBCF6AA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_307BFABFB1C9FB0D926A816A7EBC7449" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_5C213AA35070C7369424816A7EBCF6AA" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_307BFABFB1C9FB0D926A816A7EBC7449" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_9B6B2104FEE44676B246816A7EBCB425" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_5C213AA35070C7369424816A7EBCF6AA" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_9B6B2104FEE44676B246816A7EBCB425" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_1A0FBF329FD58B1D810E816A7EBCFF63" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_1A0FBF329FD58B1D810E816A7EBCFF63" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_279CC1CFB14391090CF2816A7EBC11F5" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_279CC1CFB14391090CF2816A7EBC11F5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_CADF7CB4935EF326513C816A7EBCC8EF" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_CADF7CB4935EF326513C816A7EBCC8EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_C963427C9E0B17CD9746816A7EBC1177" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_C963427C9E0B17CD9746816A7EBC1177" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DividendsPreferredStockCash" xlink:label="loc_us-gaap_DividendsPreferredStockCash_20F1A372E0BC3ADFCE1A816A7EBC2F57" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_DividendsPreferredStockCash_20F1A372E0BC3ADFCE1A816A7EBC2F57" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DividendsCommonStockCash" xlink:label="loc_us-gaap_DividendsCommonStockCash_B3C76A0049AB00A7AC39816A7EBCDE59" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_FE7DE73285D34675992E816A7EBC86FA" xlink:to="loc_us-gaap_DividendsCommonStockCash_B3C76A0049AB00A7AC39816A7EBCDE59" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstruments" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_73CB7A2B52D925227299816A7CC5EFDA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_PositionAxis_73CB7A2B52D925227299816A7CC5EFDA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_73CB7A2B52D925227299816A7CC5EFDA" xlink:to="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_73CB7A2B52D925227299816A7CC5EFDA" xlink:to="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_30C079EFDBD83B584A3E816A7CC5F18E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542" xlink:to="loc_us-gaap_ShortMember_30C079EFDBD83B584A3E816A7CC5F18E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongMember" xlink:label="loc_us-gaap_LongMember_3CE2CC63599E217494A8816A7CC51511" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_45E16D9E097280DBF342816A7CC5F542" xlink:to="loc_us-gaap_LongMember_3CE2CC63599E217494A8816A7CC51511" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_866B41D69739745A9B3E816A7CC5F2CC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_HedgingDesignationAxis_866B41D69739745A9B3E816A7CC5F2CC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_0D6A690D56BAA6D6718C816A7CC508CD_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_866B41D69739745A9B3E816A7CC5F2CC" xlink:to="loc_us-gaap_HedgingDesignationDomain_0D6A690D56BAA6D6718C816A7CC508CD_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_0D6A690D56BAA6D6718C816A7CC508CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_866B41D69739745A9B3E816A7CC5F2CC" xlink:to="loc_us-gaap_HedgingDesignationDomain_0D6A690D56BAA6D6718C816A7CC508CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_ECA28CA66CC6D1491F24816A7CC53F26" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_0D6A690D56BAA6D6718C816A7CC508CD" xlink:to="loc_us-gaap_NondesignatedMember_ECA28CA66CC6D1491F24816A7CC53F26" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_88DCF46A224BCFBE1557816A7CC58D43" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_InvestmentTypeAxis_88DCF46A224BCFBE1557816A7CC58D43" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_88DCF46A224BCFBE1557816A7CC58D43" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_88DCF46A224BCFBE1557816A7CC58D43" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OtherDerivativesMember" xlink:label="loc_agnc_OtherDerivativesMember_20CD9A36ED10910E004B816A7CC5C596" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA" xlink:to="loc_agnc_OtherDerivativesMember_20CD9A36ED10910E004B816A7CC5C596" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_3A106B6C3AFC9F296B3F816A7CC5E892" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_E0ED04C1F4FCAFB5DD5E816A7CC5FCFA" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_3A106B6C3AFC9F296B3F816A7CC5E892" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_2CC246A39D0FB91BF315816A7CC5F6B5" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_DerivativeByNatureAxis_2CC246A39D0FB91BF315816A7CC5F6B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_2CC246A39D0FB91BF315816A7CC5F6B5" xlink:to="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_2CC246A39D0FB91BF315816A7CC5F6B5" xlink:to="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_62EDD694C6798394D7B5816A7CC5733A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6" xlink:to="loc_agnc_ReceiverSwaptionMember_62EDD694C6798394D7B5816A7CC5733A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_E3E31E80D32BB6F89B9A816A7CC50373" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6" xlink:to="loc_agnc_PayerSwaptionMember_E3E31E80D32BB6F89B9A816A7CC50373" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_CDFC928B44327C754A86816A7CC580C3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_90A8905FFFD30E4BA706816A7CC5A4A6" xlink:to="loc_us-gaap_FutureMember_CDFC928B44327C754A86816A7CC580C3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_291A8B730C1518B79322816A7CC5DB0A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_291A8B730C1518B79322816A7CC5DB0A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_291A8B730C1518B79322816A7CC5DB0A" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_291A8B730C1518B79322816A7CC5DB0A" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_C9F4C7B8BF8B51425742816A7CC58D03" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_us-gaap_InterestRateSwaptionMember_C9F4C7B8BF8B51425742816A7CC58D03" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_715803A2A11BCE08D873816A7CC5370E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_agnc_ReceiverSwaptionMember_715803A2A11BCE08D873816A7CC5370E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_BA6AC49C5D348A4366E2816A7CC579E7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_agnc_PayerSwaptionMember_BA6AC49C5D348A4366E2816A7CC579E7" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_C0446F09E8A2057F3FA4816A7CC501BC" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_C0446F09E8A2057F3FA4816A7CC501BC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_A9BBB31B2B1BFA10834F816A7CC51F39" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_A9BBB31B2B1BFA10834F816A7CC51F39" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_1C0DD33389178D0E357C816A7CC57B0F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_us-gaap_InterestRateSwapMember_1C0DD33389178D0E357C816A7CC57B0F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_238DD5B7E67EA014739F816A7CC58DC0" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2326E94A8D9507A0DB7D816A7CC59120" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_238DD5B7E67EA014739F816A7CC58DC0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_356F32F66D1EDF9357F0816A7CC5043B" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_356F32F66D1EDF9357F0816A7CC5043B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_356F32F66D1EDF9357F0816A7CC5043B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_356F32F66D1EDF9357F0816A7CC5043B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_18E7F2A3E81F1103A7DA816A7CC54908" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_18E7F2A3E81F1103A7DA816A7CC54908" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_7476DBBAB4346D8EF1F0816A7CC546DE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_us-gaap_InterestRateSwapMember_7476DBBAB4346D8EF1F0816A7CC546DE" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_F42F55A8F5E93FA1612F816A7CC5B795" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_F42F55A8F5E93FA1612F816A7CC5B795" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateSwapsMember" xlink:label="loc_agnc_InterestRateSwapsMember_62FCCCB0337F68F0F4CC816A7CC5C36E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_agnc_InterestRateSwapsMember_62FCCCB0337F68F0F4CC816A7CC5C36E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_49CBBB8837F16FB1BE9F816A7CC50B0F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_agnc_ReceiverSwaptionMember_49CBBB8837F16FB1BE9F816A7CC50B0F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_BB740888A5F71DBE7460816A7CC5C7CC" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1CA1E4032DFB855F0165816A7CC53C7A" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_BB740888A5F71DBE7460816A7CC5C7CC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeAxis" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_2AEEA46EA789C9454C02816A7CCF7F40" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4FF118B1B2102053084D816A7CC5C7DD" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_2AEEA46EA789C9454C02816A7CCF7F40" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_FFFD4AF611FF8C6A8B2A816A7CCF3EC3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_2AEEA46EA789C9454C02816A7CCF7F40" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_FFFD4AF611FF8C6A8B2A816A7CCF3EC3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_FFFD4AF611FF8C6A8B2A816A7CCF3EC3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_2AEEA46EA789C9454C02816A7CCF7F40" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_FFFD4AF611FF8C6A8B2A816A7CCF3EC3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward" xlink:label="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_710710CB484B05888735816A7CCF62CB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_710710CB484B05888735816A7CCF62CB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_3034F91775686C487EDF816A7CCF5C27" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_710710CB484B05888735816A7CCF62CB" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_3034F91775686C487EDF816A7CCF5C27" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_87E4380E0FA46C5F39A0816A7CCF9887" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_710710CB484B05888735816A7CCF62CB" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_87E4380E0FA46C5F39A0816A7CCF9887" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_B7F9614F708DBCE58CD5816A7CCF8644" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_710710CB484B05888735816A7CCF62CB" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_B7F9614F708DBCE58CD5816A7CCF8644" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_92BB8C541CF6E6E7A0E9816A7CCFAA31" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_92BB8C541CF6E6E7A0E9816A7CCFAA31" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecurities" xlink:label="loc_us-gaap_TradingSecurities_CFB257A0040706597068816A7CCFC983" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_us-gaap_TradingSecurities_CFB257A0040706597068816A7CCFC983" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TradingSecuritiesAddedDuringthePeriod" xlink:label="loc_agnc_TradingSecuritiesAddedDuringthePeriod_EFF9E57D748E4953C419816A7CCF2C0B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_agnc_TradingSecuritiesAddedDuringthePeriod_EFF9E57D748E4953C419816A7CCF2C0B" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod" xlink:label="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_307D1204690BC4B9A8D7816A7CCFD9F3" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_307D1204690BC4B9A8D7816A7CCFD9F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_B4BE4B461BE45AC6DC74816A7CCFC366" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_B4BE4B461BE45AC6DC74816A7CCFC366" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GainlossonREITEquitySecurities" xlink:label="loc_agnc_GainlossonREITEquitySecurities_2F595C6F25E4592F2C59816A7CCFCDB4" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_agnc_GainlossonREITEquitySecurities_2F595C6F25E4592F2C59816A7CCFCDB4" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GainLossOnOtherDebt" xlink:label="loc_agnc_GainLossOnOtherDebt_0F270884B93446DC8D55816A7CCFC3C5" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D637D778219AF4ECFDD2816A7CCF1C5B" xlink:to="loc_agnc_GainLossOnOtherDebt_0F270884B93446DC8D55816A7CCFC3C5" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_DB477236FCE064CFBDDE816A7D3EA542" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_PositionAxis_DB477236FCE064CFBDDE816A7D3EA542" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_DB477236FCE064CFBDDE816A7D3EA542" xlink:to="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_DB477236FCE064CFBDDE816A7D3EA542" xlink:to="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_CA8B742DDBC7B6EF9BC2816A7D488401" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7" xlink:to="loc_us-gaap_ShortMember_CA8B742DDBC7B6EF9BC2816A7D488401" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongMember" xlink:label="loc_us-gaap_LongMember_786C210D05BC4DA6806F816A7D48C10C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_3B9B4F42EA8F07251D17816A7D3E6BA7" xlink:to="loc_us-gaap_LongMember_786C210D05BC4DA6806F816A7D48C10C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_0FDDC9459009949DD074816A7D480EFA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_HedgingDesignationAxis_0FDDC9459009949DD074816A7D480EFA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_AA8B00FFF57D4B791908816A7D480384_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_0FDDC9459009949DD074816A7D480EFA" xlink:to="loc_us-gaap_HedgingDesignationDomain_AA8B00FFF57D4B791908816A7D480384_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_AA8B00FFF57D4B791908816A7D480384" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_0FDDC9459009949DD074816A7D480EFA" xlink:to="loc_us-gaap_HedgingDesignationDomain_AA8B00FFF57D4B791908816A7D480384" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_ACD5A8115BF7CD339264816A7D484C6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_AA8B00FFF57D4B791908816A7D480384" xlink:to="loc_us-gaap_NondesignatedMember_ACD5A8115BF7CD339264816A7D484C6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_738D62C8C73EAC2A4E58816A7D48784B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_738D62C8C73EAC2A4E58816A7D48784B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_738D62C8C73EAC2A4E58816A7D48784B" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_738D62C8C73EAC2A4E58816A7D48784B" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_43D6F094AC663DB314AB816A7D489E6A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_43D6F094AC663DB314AB816A7D489E6A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_BA52285C640F3D65BB1D816A7D485B18" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9769AA3693C00F72ED82816A7D481551" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_BA52285C640F3D65BB1D816A7D485B18" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_AC868451346957C669CE816A7D484184" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_AC868451346957C669CE816A7D484184" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_B1BC920B5F12FDF76F7F816A7D48C100_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_AC868451346957C669CE816A7D484184" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_B1BC920B5F12FDF76F7F816A7D48C100_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_B1BC920B5F12FDF76F7F816A7D48C100" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_AC868451346957C669CE816A7D484184" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_B1BC920B5F12FDF76F7F816A7D48C100" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_FDE305EAB2FEBB2D0CA8816A7D488F4E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_B1BC920B5F12FDF76F7F816A7D48C100" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_FDE305EAB2FEBB2D0CA8816A7D488F4E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_49E527DAF6A5397FE245816A7D489196" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_49E527DAF6A5397FE245816A7D489196" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_49E527DAF6A5397FE245816A7D489196" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_49E527DAF6A5397FE245816A7D489196" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_2A797D98AA0DC543C350816A7D48A321" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_2A797D98AA0DC543C350816A7D48A321" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_68E240019462A0BA7605816A7D481B15" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_us-gaap_InterestRateSwapMember_68E240019462A0BA7605816A7D481B15" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_01B861F20BBC4DF9F0A2816A7D48105D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_us-gaap_InterestRateSwaptionMember_01B861F20BBC4DF9F0A2816A7D48105D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_89FC9AC7BBB3408BBBF1816A7D48FD15" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_89FC9AC7BBB3408BBBF1816A7D48FD15" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_8F64AFCF1FC3D9790701816A7D48B547" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_us-gaap_FutureMember_8F64AFCF1FC3D9790701816A7D48B547" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_8A81A949A1949C58716B816A7D489B8E" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_agnc_ReceiverSwaptionMember_8A81A949A1949C58716B816A7D489B8E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_CA87FCE7151F0E02446B816A7D48FE0E" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_371014324A917613A443816A7D48E2BD" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_CA87FCE7151F0E02446B816A7D48FE0E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6AD7E3B82633BB4E5E05816A7D4802D8" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6AD7E3B82633BB4E5E05816A7D4802D8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6AD7E3B82633BB4E5E05816A7D4802D8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6AD7E3B82633BB4E5E05816A7D4802D8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_8F2D6072721348EC0F15816A7D481AE9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_8F2D6072721348EC0F15816A7D481AE9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_4735FE6BCA80BEB6291A816A7D48E00B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_704F954078CB1129A52D816A7D487C20" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_4735FE6BCA80BEB6291A816A7D48E00B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_5D62C839B830AF74190C816A7D481B38" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_983F1E48C808AC6911F1816A7D3EE828" xlink:to="loc_us-gaap_DerivativeByNatureAxis_5D62C839B830AF74190C816A7D481B38" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_5D62C839B830AF74190C816A7D481B38" xlink:to="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_5D62C839B830AF74190C816A7D481B38" xlink:to="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_0E1C6EB54A1C37942E76816A7D48E7EE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA" xlink:to="loc_us-gaap_FutureMember_0E1C6EB54A1C37942E76816A7D48E7EE" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_4C7B1E591AD2F84DC4F4816A7D48059D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA" xlink:to="loc_agnc_ReceiverSwaptionMember_4C7B1E591AD2F84DC4F4816A7D48059D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_3052B9BBEA69782FAB4D816A7D48DF00" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_0AF29A6EF3DB652F3E2D816A7D48E0BA" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_3052B9BBEA69782FAB4D816A7D48DF00" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_DDDBD86EC3973C2AD490816A7D487DEF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_DDDBD86EC3973C2AD490816A7D487DEF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_9A2534CA39E7E88B82E3816A7D48EECA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_9A2534CA39E7E88B82E3816A7D48EECA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_4EC7F35C8E2E13A67812816A7D48BC2E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_4EC7F35C8E2E13A67812816A7D48BC2E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_ACDEEF6D7892E4A3265E816A7D488915" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeAssets_ACDEEF6D7892E4A3265E816A7D488915" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaap_DerivativeLiabilities_3F35135867ADAC53EA12816A7D480B20" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeLiabilities_3F35135867ADAC53EA12816A7D480B20" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_E8766D31C7C169D586E8816A7D482529" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_E8766D31C7C169D586E8816A7D482529" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations" xlink:label="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations_4E90385D56DED1293DB0816A7D48AAF2" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations_4E90385D56DED1293DB0816A7D48AAF2" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_Governmentbondsownedandsoldshortnet" xlink:label="loc_agnc_Governmentbondsownedandsoldshortnet_48F0111B32E10D99E67A816A7D48A422" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_agnc_Governmentbondsownedandsoldshortnet_48F0111B32E10D99E67A816A7D48A422" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_11697751B28B56E46521816A7D489DFC" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_11697751B28B56E46521816A7D489DFC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_9E0D1E855FB3DBEB2D7A816A7D487603" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_9E0D1E855FB3DBEB2D7A816A7D487603" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_4FE0B42DC77C7814B87D816A7D48CAF0" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_4FE0B42DC77C7814B87D816A7D48CAF0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecurities" xlink:label="loc_us-gaap_TradingSecurities_FD025A49DFF3D4D0CCEE816A7D52B645" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_us-gaap_TradingSecurities_FD025A49DFF3D4D0CCEE816A7D52B645" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TradingSecuritiesAddedDuringthePeriod" xlink:label="loc_agnc_TradingSecuritiesAddedDuringthePeriod_941186D4ED7A3571F486816A7D527F0F" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_agnc_TradingSecuritiesAddedDuringthePeriod_941186D4ED7A3571F486816A7D527F0F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod" xlink:label="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_D9984C1485FCD6B6FC00816A7D524477" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10131CE1530ABD49EE52816A7D487E56" xlink:to="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_D9984C1485FCD6B6FC00816A7D524477" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_F99B16FE5B901662DD2F816A7D5D3786" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_InvestmentTypeAxis_F99B16FE5B901662DD2F816A7D5D3786" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_FC154AED24194C75116B816A7D5D62E1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_F99B16FE5B901662DD2F816A7D5D3786" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_FC154AED24194C75116B816A7D5D62E1_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_FC154AED24194C75116B816A7D5D62E1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_F99B16FE5B901662DD2F816A7D5D3786" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_FC154AED24194C75116B816A7D5D62E1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OtherDerivativesMember" xlink:label="loc_agnc_OtherDerivativesMember_2B73895C772D2B7EAC60816A7D5D3AD4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_FC154AED24194C75116B816A7D5D62E1" xlink:to="loc_agnc_OtherDerivativesMember_2B73895C772D2B7EAC60816A7D5D3AD4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_B209F2ACA4D55571B02F816A7D5D55A6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_PositionAxis_B209F2ACA4D55571B02F816A7D5D55A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_B209F2ACA4D55571B02F816A7D5D55A6" xlink:to="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_B209F2ACA4D55571B02F816A7D5D55A6" xlink:to="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_C76F2EF3010AC5234639816A7D5DC520" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B" xlink:to="loc_us-gaap_ShortMember_C76F2EF3010AC5234639816A7D5DC520" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongMember" xlink:label="loc_us-gaap_LongMember_8BBA07102948FD1F3031816A7D5D325F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_135B6C9188147E0149CF816A7D5D929B" xlink:to="loc_us-gaap_LongMember_8BBA07102948FD1F3031816A7D5D325F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_83E15E858EC21FD5B980816A7D624545" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_HedgingDesignationAxis_83E15E858EC21FD5B980816A7D624545" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_4DF7FB140E49B09AF827816A7D62E787_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_83E15E858EC21FD5B980816A7D624545" xlink:to="loc_us-gaap_HedgingDesignationDomain_4DF7FB140E49B09AF827816A7D62E787_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_4DF7FB140E49B09AF827816A7D62E787" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_83E15E858EC21FD5B980816A7D624545" xlink:to="loc_us-gaap_HedgingDesignationDomain_4DF7FB140E49B09AF827816A7D62E787" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_D0D6B2BCB11FEFCEED90816A7D621B5A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_4DF7FB140E49B09AF827816A7D62E787" xlink:to="loc_us-gaap_NondesignatedMember_D0D6B2BCB11FEFCEED90816A7D621B5A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_186DAB4129A3496C6577816A7D625854" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_DerivativeByNatureAxis_186DAB4129A3496C6577816A7D625854" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_186DAB4129A3496C6577816A7D625854" xlink:to="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_186DAB4129A3496C6577816A7D625854" xlink:to="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_415FDEAAEC1AC269E70B816A7D62F16C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2" xlink:to="loc_us-gaap_FutureMember_415FDEAAEC1AC269E70B816A7D62F16C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForwardContractsMember" xlink:label="loc_us-gaap_ForwardContractsMember_8B6DB74AD951AE9F2BF2816A7D62B439" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_5572FC1A54E6DC7D6362816A7D62FDC2" xlink:to="loc_us-gaap_ForwardContractsMember_8B6DB74AD951AE9F2BF2816A7D62B439" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_E7DB1EFFAC7DE0A130FB816A7D629979" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_agnc_DerivativePositionAxis_E7DB1EFFAC7DE0A130FB816A7D629979" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_818274F97AB0DA428AC8816A7D625609_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_E7DB1EFFAC7DE0A130FB816A7D629979" xlink:to="loc_agnc_DerivativePositionDomain_818274F97AB0DA428AC8816A7D625609_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_818274F97AB0DA428AC8816A7D625609" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_E7DB1EFFAC7DE0A130FB816A7D629979" xlink:to="loc_agnc_DerivativePositionDomain_818274F97AB0DA428AC8816A7D625609" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_C6ED35E55738EF0A7E94816A7D62F153" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_818274F97AB0DA428AC8816A7D625609" xlink:to="loc_us-gaap_InterestRateSwapMember_C6ED35E55738EF0A7E94816A7D62F153" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_1A5B2C3CA07679EA172B816A7D6328A0" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_1A5B2C3CA07679EA172B816A7D6328A0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_4F800BED920E5C070F10816A7D63CDFC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1A5B2C3CA07679EA172B816A7D6328A0" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_4F800BED920E5C070F10816A7D63CDFC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_4F800BED920E5C070F10816A7D63CDFC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1A5B2C3CA07679EA172B816A7D6328A0" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_4F800BED920E5C070F10816A7D63CDFC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_D4147F9E2F0F57731085816A7D63E7CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_4F800BED920E5C070F10816A7D63CDFC" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_D4147F9E2F0F57731085816A7D63E7CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_DCB23E9D89CE57285ED6816A7D635574" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_DCB23E9D89CE57285ED6816A7D635574" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_EF15569A3BF4E2179F4D816A7D63DCE1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_DCB23E9D89CE57285ED6816A7D635574" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_EF15569A3BF4E2179F4D816A7D63DCE1_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_EF15569A3BF4E2179F4D816A7D63DCE1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_DCB23E9D89CE57285ED6816A7D635574" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_EF15569A3BF4E2179F4D816A7D63DCE1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember" xlink:label="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_A515CB895512D1F40C24816A7D63B8A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_EF15569A3BF4E2179F4D816A7D63DCE1" xlink:to="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_A515CB895512D1F40C24816A7D63B8A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_A9A4FE36C63884FF992A816A7D63353D" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_DD7ED81B202D74756337816A7D5D5A9C" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_A9A4FE36C63884FF992A816A7D63353D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_A9A4FE36C63884FF992A816A7D63353D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_A9A4FE36C63884FF992A816A7D63353D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_8B0328BE35CD568D1FD6816A7D6382D5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:to="loc_us-gaap_InterestRateSwaptionMember_8B0328BE35CD568D1FD6816A7D6382D5" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_BFDA5C1D65F9845B821B816A7D639388" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_BFDA5C1D65F9845B821B816A7D639388" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateSwapsMember" xlink:label="loc_agnc_InterestRateSwapsMember_C155495C853E1B1142CC816A7D63111A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:to="loc_agnc_InterestRateSwapsMember_C155495C853E1B1142CC816A7D63111A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_E74CEE48E2E07922C9B4816A7D63E015" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:to="loc_us-gaap_InterestRateSwapMember_E74CEE48E2E07922C9B4816A7D63E015" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_1179B5CE9F894AB5D6A8816A7D63FE3B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13D4C2C4E426D1C03A85816A7D633C20" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_1179B5CE9F894AB5D6A8816A7D63FE3B" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GainLossOnOtherDebt" xlink:label="loc_agnc_GainLossOnOtherDebt_09A401E96A1874B52F95816A7D63C033" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_GainLossOnOtherDebt_09A401E96A1874B52F95816A7D63C033" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_C8D6E4A90B43F70A74A5816A7D63556A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_C8D6E4A90B43F70A74A5816A7D63556A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NetPeriodicInterestRateCostsOnSwaps" xlink:label="loc_agnc_NetPeriodicInterestRateCostsOnSwaps_331481B4682362124B8B816A7D638047" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_NetPeriodicInterestRateCostsOnSwaps_331481B4682362124B8B816A7D638047" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion" xlink:label="loc_us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion_9F1F7B76C36D7AA9CC63816A7D6309FB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion_9F1F7B76C36D7AA9CC63816A7D6309FB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge" xlink:label="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_D04A56E7FE77F7EEE8F9816A7D632E11" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_D04A56E7FE77F7EEE8F9816A7D632E11" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_A84181A71DABE8964734816A7D634965" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_A84181A71DABE8964734816A7D634965" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_C8923300C78DC874BEEC816A7D63282A" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_C8923300C78DC874BEEC816A7D63282A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration" xlink:label="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_8FADD3661519D5531BD1816A7D635EFE" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_8FADD3661519D5531BD1816A7D635EFE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_AA1A3CF86CBDEC40061F816A7D633A88" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_AA1A3CF86CBDEC40061F816A7D633A88" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_E1C4D3B8E26DB3DBDC85816A7D63799C" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_E1C4D3B8E26DB3DBDC85816A7D63799C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GainlossonREITEquitySecurities" xlink:label="loc_agnc_GainlossonREITEquitySecurities_D960D5759856F288829E816A7D64EA27" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_GainlossonREITEquitySecurities_D960D5759856F288829E816A7D64EA27" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_074D86E7609667553D07816A7D69C4EF" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_074D86E7609667553D07816A7D69C4EF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_DEB9FEA2C5D0A8DD6B02816A7D69D234" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_DEB9FEA2C5D0A8DD6B02816A7D69D234" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_2017E30400F8E19B00A7816A7D69811F" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_2017E30400F8E19B00A7816A7D69811F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateDerivativesAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativesAtFairValueNet_DE0A7D5CC19860672222816A7D699364" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_InterestRateDerivativesAtFairValueNet_DE0A7D5CC19860672222816A7D699364" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_DC390C8DBBE0A93375CA816A7D699B56" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_OptionsAtCost_DC390C8DBBE0A93375CA816A7D699B56" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate" xlink:label="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_B2051A084E9B4529A7ED816A7D698ED2" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_B2051A084E9B4529A7ED816A7D698ED2" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TradingSecuritiesAddedDuringthePeriod" xlink:label="loc_agnc_TradingSecuritiesAddedDuringthePeriod_3579FED317C40E79EE3A816A7D69139E" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_TradingSecuritiesAddedDuringthePeriod_3579FED317C40E79EE3A816A7D69139E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod" xlink:label="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_FAD74C8618D8E1F05000816A7D69C948" xlink:type="locator" />
    <definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_FAD74C8618D8E1F05000816A7D69C948" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecurities" xlink:label="loc_us-gaap_TradingSecurities_868682E57052CACD2AAE816A7D695E18" xlink:type="locator" />
    <definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_731F5F0EA79A9D926DEA816A7D6339C8" xlink:to="loc_us-gaap_TradingSecurities_868682E57052CACD2AAE816A7D695E18" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_A022A6C045108B769EDA14DC6C733160" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_us-gaap_DerivativeTable_A022A6C045108B769EDA14DC6C733160" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityAxis" xlink:label="loc_agnc_DerivativesByMaturityAxis_3C0F8230F54DE8D351A014DC6C73F65C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_A022A6C045108B769EDA14DC6C733160" xlink:to="loc_agnc_DerivativesByMaturityAxis_3C0F8230F54DE8D351A014DC6C73F65C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativesByMaturityAxis_3C0F8230F54DE8D351A014DC6C73F65C" xlink:to="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativesByMaturityAxis_3C0F8230F54DE8D351A014DC6C73F65C" xlink:to="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_LessThanOrEqualToOneYearMember" xlink:label="loc_agnc_LessThanOrEqualToOneYearMember_7BF4C27D49A14C576CDD14DC6C73E999" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D" xlink:to="loc_agnc_LessThanOrEqualToOneYearMember_7BF4C27D49A14C576CDD14DC6C73E999" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_9D240B3DA3DA3387D76814DC6C7318CA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_40E55EB36D4363E6FB4F14DC6C73DA3D" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_9D240B3DA3DA3387D76814DC6C7318CA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_C841206AECDE5DFDD3F314DC6C73B60D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_A022A6C045108B769EDA14DC6C733160" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_C841206AECDE5DFDD3F314DC6C73B60D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_C841206AECDE5DFDD3F314DC6C73B60D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_C841206AECDE5DFDD3F314DC6C73B60D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_062FE44613262603321B14DC6C7350BA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8" xlink:to="loc_us-gaap_InterestRateSwaptionMember_062FE44613262603321B14DC6C7350BA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_03FE4F87798CB1B3466614DC6C738BB8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8" xlink:to="loc_agnc_ReceiverSwaptionMember_03FE4F87798CB1B3466614DC6C738BB8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_CB88D942EC28DA21B53114DC6C73A522" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_620432EE641817C0D40814DC6C737AC8" xlink:to="loc_agnc_PayerSwaptionMember_CB88D942EC28DA21B53114DC6C73A522" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_C20B5B17FE70EB5E071314DC6C7370F3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_agnc_OptionsAtCost_C20B5B17FE70EB5E071314DC6C7370F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateDerivativesAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativesAtFairValueNet_35A9C3690498A36DD53314DC6C737BDC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_us-gaap_InterestRateDerivativesAtFairValueNet_35A9C3690498A36DD53314DC6C737BDC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration" xlink:label="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_24C268D0744CB72DF79414DC6C739130" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_24C268D0744CB72DF79414DC6C739130" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_9C8049B686B48F9B671D14DC6C73E462" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_9C8049B686B48F9B671D14DC6C73E462" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_67932D7FC4E683FC177D14DC6C736B84" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_67932D7FC4E683FC177D14DC6C736B84" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate" xlink:label="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_ED147BBDAADF6E9B7EC414DC6C73ED60" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_ED147BBDAADF6E9B7EC414DC6C73ED60" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_5B8218F7CCED2BCB2E2814DC6C7301B0" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4FE342A303D93501BD2C14DC6C73329A" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_5B8218F7CCED2BCB2E2814DC6C7301B0" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityAxis" xlink:label="loc_agnc_DerivativesByMaturityAxis_5AF659867ED1AE8553EF7C6677952318" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:to="loc_agnc_DerivativesByMaturityAxis_5AF659867ED1AE8553EF7C6677952318" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativesByMaturityAxis_5AF659867ED1AE8553EF7C6677952318" xlink:to="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativesByMaturityAxis_5AF659867ED1AE8553EF7C6677952318" xlink:to="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_LessThanOrEqualToOneYearMember" xlink:label="loc_agnc_LessThanOrEqualToOneYearMember_3C3A7D36EAD4397806DD7C667795ACA2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_LessThanOrEqualToOneYearMember_3C3A7D36EAD4397806DD7C667795ACA2" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_D54A0877545E6E15FED97C66779500E1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_D54A0877545E6E15FED97C66779500E1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember" xlink:label="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_15504561FC995DCDBC757C667795C29A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_15504561FC995DCDBC757C667795C29A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember" xlink:label="loc_agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember_CDB412C48E51561027FA7C667795D5ED" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember_CDB412C48E51561027FA7C667795D5ED" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember" xlink:label="loc_agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember_7D3A09725E02FA0289CC7C667795E1BB" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember_7D3A09725E02FA0289CC7C667795E1BB" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanTenYearsMember" xlink:label="loc_agnc_GreaterThanTenYearsMember_C00A50FDFAC221AC5B087C6677959F90" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_11401C754AFCE95DC16A7C667795C6F1" xlink:to="loc_agnc_GreaterThanTenYearsMember_C00A50FDFAC221AC5B087C6677959F90" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_59FF24062A873AD415F07C667795BFEF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:to="loc_us-gaap_DerivativeByNatureAxis_59FF24062A873AD415F07C667795BFEF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_59FF24062A873AD415F07C667795BFEF" xlink:to="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_59FF24062A873AD415F07C667795BFEF" xlink:to="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ForwardContractsMember" xlink:label="loc_us-gaap_ForwardContractsMember_553813376B8C69E9E5627C6677957589" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C" xlink:to="loc_us-gaap_ForwardContractsMember_553813376B8C69E9E5627C6677957589" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateSwapsExcludingForwardStartingMember" xlink:label="loc_agnc_InterestRateSwapsExcludingForwardStartingMember_F4BDC4A841C4C7E53C0E7C6677951C86" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_66A8E456F58F235156467C667795FA1C" xlink:to="loc_agnc_InterestRateSwapsExcludingForwardStartingMember_F4BDC4A841C4C7E53C0E7C6677951C86" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_2BCFE6EDC24AF1F413187C6677955B1A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:to="loc_agnc_DerivativePositionAxis_2BCFE6EDC24AF1F413187C6677955B1A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_28255E75B144D6A0114A7C6677954DC8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_2BCFE6EDC24AF1F413187C6677955B1A" xlink:to="loc_agnc_DerivativePositionDomain_28255E75B144D6A0114A7C6677954DC8_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_28255E75B144D6A0114A7C6677954DC8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_2BCFE6EDC24AF1F413187C6677955B1A" xlink:to="loc_agnc_DerivativePositionDomain_28255E75B144D6A0114A7C6677954DC8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_E948A9B4872426217BBB7C6677953818" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_28255E75B144D6A0114A7C6677954DC8" xlink:to="loc_us-gaap_InterestRateSwapMember_E948A9B4872426217BBB7C6677953818" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_B0E5668E35D0D66888737C667795BEF5" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_74B76B8E3C2632730ADF7C6677951876" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_B0E5668E35D0D66888737C667795BEF5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5A839B38563A17618E297C66779526EA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B0E5668E35D0D66888737C667795BEF5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5A839B38563A17618E297C66779526EA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5A839B38563A17618E297C66779526EA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B0E5668E35D0D66888737C667795BEF5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5A839B38563A17618E297C66779526EA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_92C8ADB53038D7E535F37C6677955D95" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5A839B38563A17618E297C66779526EA" xlink:to="loc_us-gaap_InterestRateSwapMember_92C8ADB53038D7E535F37C6677955D95" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_72CEEA875FAC3B5DF5A07C6677955192" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_72CEEA875FAC3B5DF5A07C6677955192" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_621D3147C15BED8D5E627C66779595FB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_621D3147C15BED8D5E627C66779595FB" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_F7E954CE57B558DB7C5E7C6677959F0C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_agnc_OptionsAtCost_F7E954CE57B558DB7C5E7C6677959F0C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageVariableInterestRate" xlink:label="loc_us-gaap_DerivativeAverageVariableInterestRate_EC2103056E3B3D5DE19A7C6677950878" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeAverageVariableInterestRate_EC2103056E3B3D5DE19A7C6677950878" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet_DD28971494354B39751A7C667795F7BF" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet_DD28971494354B39751A7C667795F7BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_2CB429E6D9573EE7227B7C667795131E" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_2CB429E6D9573EE7227B7C667795131E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_7CF90CBBE09767FD7DE07C6677957DBA" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_invest_DerivativeNotionalAmount_7CF90CBBE09767FD7DE07C6677957DBA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeHigherRemainingMaturityRange1" xlink:label="loc_us-gaap_DerivativeHigherRemainingMaturityRange1_45D6F3688781428706EF7C667795F5F2" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98DC6FD71E6C6F4FC7047C667795A1D5" xlink:to="loc_us-gaap_DerivativeHigherRemainingMaturityRange1_45D6F3688781428706EF7C667795F5F2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTables" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_9EB14F8386FE01A183B514DC6BA83099" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_us-gaap_DerivativeTable_9EB14F8386FE01A183B514DC6BA83099" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_65BDCDE22FC0FDAA17DF14DC6BA8FCF6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9EB14F8386FE01A183B514DC6BA83099" xlink:to="loc_us-gaap_HedgingDesignationAxis_65BDCDE22FC0FDAA17DF14DC6BA8FCF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_BE72A6F3833EEAF7633114DC6BA8F973_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_65BDCDE22FC0FDAA17DF14DC6BA8FCF6" xlink:to="loc_us-gaap_HedgingDesignationDomain_BE72A6F3833EEAF7633114DC6BA8F973_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_BE72A6F3833EEAF7633114DC6BA8F973" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_65BDCDE22FC0FDAA17DF14DC6BA8FCF6" xlink:to="loc_us-gaap_HedgingDesignationDomain_BE72A6F3833EEAF7633114DC6BA8F973" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_AEDB216AC5B13AA4C9D514DC6BA89231" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_BE72A6F3833EEAF7633114DC6BA8F973" xlink:to="loc_us-gaap_NondesignatedMember_AEDB216AC5B13AA4C9D514DC6BA89231" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock_32A0B1F3D5D0C2D2F60914DC6BA8A58A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock_32A0B1F3D5D0C2D2F60914DC6BA8A58A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock" xlink:label="loc_agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock_C735D13406E8DF5E664A14DC6BA81CC1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock_C735D13406E8DF5E664A14DC6BA81CC1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock" xlink:label="loc_agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock_68F5609D26FC7BE4F45714DC6BA8322A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock_68F5609D26FC7BE4F45714DC6BA8322A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_USgovernmentsecuritiesTableTextBlock" xlink:label="loc_agnc_USgovernmentsecuritiesTableTextBlock_F0B0E77BB138337E112914DC6BA85EC0" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_USgovernmentsecuritiesTableTextBlock_F0B0E77BB138337E112914DC6BA85EC0" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_USGovernmentFuturesSecuritiesTableTextBlock" xlink:label="loc_agnc_USGovernmentFuturesSecuritiesTableTextBlock_CB22C6DD281EF2DFF1FF14DC6BA8FE6E" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_USGovernmentFuturesSecuritiesTableTextBlock_CB22C6DD281EF2DFF1FF14DC6BA8FE6E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock_1039F83E188C47649FD814DC6BA8279F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock_1039F83E188C47649FD814DC6BA8279F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock_96FF24584FB0EE846FAB14DC6BA8E5DC" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1D1EC0A668E1E53B53C814DC6BA85E9A" xlink:to="loc_agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock_96FF24584FB0EE846FAB14DC6BA8E5DC" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:to="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_88673AAA98C77091578E62C053665C1A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:to="loc_us-gaap_PositionAxis_88673AAA98C77091578E62C053665C1A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_98DA0FEF09BCBA1CF62B62C053666194_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_88673AAA98C77091578E62C053665C1A" xlink:to="loc_us-gaap_PositionDomain_98DA0FEF09BCBA1CF62B62C053666194_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_98DA0FEF09BCBA1CF62B62C053666194" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_88673AAA98C77091578E62C053665C1A" xlink:to="loc_us-gaap_PositionDomain_98DA0FEF09BCBA1CF62B62C053666194" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_74B5715430DF5C2ADE0D62C05366730F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_98DA0FEF09BCBA1CF62B62C053666194" xlink:to="loc_us-gaap_ShortMember_74B5715430DF5C2ADE0D62C05366730F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_0DEC07531D9CFB30731B62C05366609A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:to="loc_agnc_DerivativePositionAxis_0DEC07531D9CFB30731B62C05366609A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_0DEC07531D9CFB30731B62C05366609A" xlink:to="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_0DEC07531D9CFB30731B62C05366609A" xlink:to="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A2.5CouponMember" xlink:label="loc_agnc_A2.5CouponMember_C8B1878CB021A578906262C05367987D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:to="loc_agnc_A2.5CouponMember_C8B1878CB021A578906262C05367987D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A3.0CouponMember" xlink:label="loc_agnc_A3.0CouponMember_D0B6649FFC337E94B85262C0536722A7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:to="loc_agnc_A3.0CouponMember_D0B6649FFC337E94B85262C0536722A7" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A3.5CouponMember" xlink:label="loc_agnc_A3.5CouponMember_0B442080E4ECEDF9170E62C05367FDAC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:to="loc_agnc_A3.5CouponMember_0B442080E4ECEDF9170E62C05367FDAC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A4.0CouponMember" xlink:label="loc_agnc_A4.0CouponMember_74E1087195DF63E69A8A62C05367F077" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:to="loc_agnc_A4.0CouponMember_74E1087195DF63E69A8A62C05367F077" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A4.5CouponMember" xlink:label="loc_agnc_A4.5CouponMember_A4403ACF472EA1B4323D62C053677DC5" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D3E87A8A470B0368896162C053667AF0" xlink:to="loc_agnc_A4.5CouponMember_A4403ACF472EA1B4323D62C053677DC5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_F8DA682FE4AA7FF4503262C053670196" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_F8DA682FE4AA7FF4503262C053670196" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_F3DAF07C3DAD2C18154562C05367DD05_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_F8DA682FE4AA7FF4503262C053670196" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_F3DAF07C3DAD2C18154562C05367DD05_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_F3DAF07C3DAD2C18154562C05367DD05" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_F8DA682FE4AA7FF4503262C053670196" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_F3DAF07C3DAD2C18154562C05367DD05" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_04CFDC042C85AFCA4DF662C053674F46" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_F3DAF07C3DAD2C18154562C05367DD05" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_04CFDC042C85AFCA4DF662C053674F46" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_D1DBF5D43A521CBC2DE462C053675C8B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_148028E87021FAD9460462C053660C0F" xlink:to="loc_us-gaap_DerivativeByNatureAxis_D1DBF5D43A521CBC2DE462C053675C8B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_D1DBF5D43A521CBC2DE462C053675C8B" xlink:to="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_D1DBF5D43A521CBC2DE462C053675C8B" xlink:to="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A15YearMaturityMember" xlink:label="loc_agnc_A15YearMaturityMember_8A8E92F0DAA8CF87C3A962C053676162" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:to="loc_agnc_A15YearMaturityMember_8A8E92F0DAA8CF87C3A962C053676162" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A30YearMaturityMember" xlink:label="loc_agnc_A30YearMaturityMember_B391BEAA8BF6328FD3E862C05367C095" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:to="loc_agnc_A30YearMaturityMember_B391BEAA8BF6328FD3E862C05367C095" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember" xlink:label="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_074A7E1F5CE9E371DD5162C0536740EF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:to="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_074A7E1F5CE9E371DD5162C0536740EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_342391DD9FB2BF1A275862C053674CEF" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_342391DD9FB2BF1A275862C053674CEF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember" xlink:label="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_98C80B2BF47DA0848B3362C05367A016" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_ACDFED4275CC5069EA8F62C05367607C" xlink:to="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_98C80B2BF47DA0848B3362C05367A016" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_DF8E5540337215959C7E62C053678DEE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:to="loc_invest_DerivativeNotionalAmount_DF8E5540337215959C7E62C053678DEE" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativeForwardSettlementValue" xlink:label="loc_agnc_DerivativeForwardSettlementValue_7EBB90BEB5DE12E0FBA162C053674D45" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:to="loc_agnc_DerivativeForwardSettlementValue_7EBB90BEB5DE12E0FBA162C053674D45" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_C5E427264AE7C3E8621962C053673C1E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_C5E427264AE7C3E8621962C053673C1E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_54578840BAE0C2A6D6D362C05367DEC8" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_021ACF441255E1D183C962C05367B9FF" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_54578840BAE0C2A6D6D362C05367DEC8" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_DD217C30DABF84C2D67214DC6DB98C62" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_us-gaap_PositionAxis_DD217C30DABF84C2D67214DC6DB98C62" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_F4A964A847D6CE40BC4A14DC6DB926B3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_DD217C30DABF84C2D67214DC6DB98C62" xlink:to="loc_us-gaap_PositionDomain_F4A964A847D6CE40BC4A14DC6DB926B3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_F4A964A847D6CE40BC4A14DC6DB926B3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_DD217C30DABF84C2D67214DC6DB98C62" xlink:to="loc_us-gaap_PositionDomain_F4A964A847D6CE40BC4A14DC6DB926B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_1AC023E8611255E469A614DC6DB940E9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_F4A964A847D6CE40BC4A14DC6DB926B3" xlink:to="loc_us-gaap_ShortMember_1AC023E8611255E469A614DC6DB940E9" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityAxis" xlink:label="loc_agnc_DerivativesByMaturityAxis_63545066604F35F0216414DC6DB90AD0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_agnc_DerivativesByMaturityAxis_63545066604F35F0216414DC6DB90AD0" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativesByMaturityAxis_63545066604F35F0216414DC6DB90AD0" xlink:to="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativesByMaturityAxis_63545066604F35F0216414DC6DB90AD0" xlink:to="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A10YearMaturityMember" xlink:label="loc_agnc_A10YearMaturityMember_048ABD8C8AB213B382C214DC6DB95CE3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452" xlink:to="loc_agnc_A10YearMaturityMember_048ABD8C8AB213B382C214DC6DB95CE3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A5YearMaturityMember" xlink:label="loc_agnc_A5YearMaturityMember_DAB6FC654989BBE7D34C14DC6DB9946C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_0102F0C3291D3C8A831914DC6DB9C452" xlink:to="loc_agnc_A5YearMaturityMember_DAB6FC654989BBE7D34C14DC6DB9946C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_495AC1298B57BEC65E5A14DC6DB990F3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_agnc_DerivativePositionAxis_495AC1298B57BEC65E5A14DC6DB990F3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_0C831539196F4CA260FA14DC6DB958B7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_495AC1298B57BEC65E5A14DC6DB990F3" xlink:to="loc_agnc_DerivativePositionDomain_0C831539196F4CA260FA14DC6DB958B7_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_0C831539196F4CA260FA14DC6DB958B7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_495AC1298B57BEC65E5A14DC6DB990F3" xlink:to="loc_agnc_DerivativePositionDomain_0C831539196F4CA260FA14DC6DB958B7" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A2.5CouponMember" xlink:label="loc_agnc_A2.5CouponMember_105CCAB369370756989714DC6DB9A6CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_0C831539196F4CA260FA14DC6DB958B7" xlink:to="loc_agnc_A2.5CouponMember_105CCAB369370756989714DC6DB9A6CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_222D5D7B0BD7796CD89714DC6DB9AD51" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_us-gaap_DerivativeByNatureAxis_222D5D7B0BD7796CD89714DC6DB9AD51" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_222D5D7B0BD7796CD89714DC6DB9AD51" xlink:to="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_222D5D7B0BD7796CD89714DC6DB9AD51" xlink:to="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_16D20E9DE84E31C7379814DC6DB9A2A1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:to="loc_us-gaap_FutureMember_16D20E9DE84E31C7379814DC6DB9A2A1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A15YearMaturityMember" xlink:label="loc_agnc_A15YearMaturityMember_54F52183EC6CDB2E2C0B14DC6DB97EF8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:to="loc_agnc_A15YearMaturityMember_54F52183EC6CDB2E2C0B14DC6DB97EF8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AtParValueMember" xlink:label="loc_agnc_AtParValueMember_C9E8264FA6013065001014DC6DB95A8F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:to="loc_agnc_AtParValueMember_C9E8264FA6013065001014DC6DB95A8F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AtCostBasisMember" xlink:label="loc_agnc_AtCostBasisMember_100365BCF5FB7D34F78614DC6DB961FC" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_DEA3A7C1673A0FF8B6A214DC6DB943DC" xlink:to="loc_agnc_AtCostBasisMember_100365BCF5FB7D34F78614DC6DB961FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7A0BB363A44D9388A5CE14DC6DB9AF8A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7A0BB363A44D9388A5CE14DC6DB9AF8A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_C6CD01883E2A163AA1CF14DC6DB96A45_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7A0BB363A44D9388A5CE14DC6DB9AF8A" xlink:to="loc_us-gaap_HedgingRelationshipDomain_C6CD01883E2A163AA1CF14DC6DB96A45_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_C6CD01883E2A163AA1CF14DC6DB96A45" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7A0BB363A44D9388A5CE14DC6DB9AF8A" xlink:to="loc_us-gaap_HedgingRelationshipDomain_C6CD01883E2A163AA1CF14DC6DB96A45" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueHedgingMember" xlink:label="loc_us-gaap_FairValueHedgingMember_3623976AEAC2F508A4C914DC6DB9809C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_C6CD01883E2A163AA1CF14DC6DB96A45" xlink:to="loc_us-gaap_FairValueHedgingMember_3623976AEAC2F508A4C914DC6DB9809C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_FD8AE75E2012CB0D086514DC6DB935EF" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2C14AF6A0A7837DD73B214DC6DB97790" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_FD8AE75E2012CB0D086514DC6DB935EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_FD8AE75E2012CB0D086514DC6DB935EF" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_FD8AE75E2012CB0D086514DC6DB935EF" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_0D89360950152FADD56314DC6DB90A77" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_0D89360950152FADD56314DC6DB90A77" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_F9D16987DD5592CBAB7514DC6DB95B1F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_F9D16987DD5592CBAB7514DC6DB95B1F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A5YearMaturityMember" xlink:label="loc_agnc_A5YearMaturityMember_11485AF4BAA4D9E92ED414DC6DB945F5" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:to="loc_agnc_A5YearMaturityMember_11485AF4BAA4D9E92ED414DC6DB945F5" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A7YearsMaturityMember" xlink:label="loc_agnc_A7YearsMaturityMember_4E607D4A5EFB1906BDCE14DC6DB9866A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:to="loc_agnc_A7YearsMaturityMember_4E607D4A5EFB1906BDCE14DC6DB9866A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A10YearMaturityMember" xlink:label="loc_agnc_A10YearMaturityMember_5817EFC6E395F83EA43814DC6DB99F5B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_AF9816FA127E1E80865314DC6DB9A390" xlink:to="loc_agnc_A10YearMaturityMember_5817EFC6E395F83EA43814DC6DB99F5B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_2B576F594484F03C238614DC6DB99EE4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_invest_DerivativeNotionalAmount_2B576F594484F03C238614DC6DB99EE4" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativeForwardSettlementValue" xlink:label="loc_agnc_DerivativeForwardSettlementValue_0A7F9575801858956A6514DC6DB9FADB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_agnc_DerivativeForwardSettlementValue_0A7F9575801858956A6514DC6DB9FADB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_E1B80FC4D5F3D79BEF0A14DC6DB90297" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_E1B80FC4D5F3D79BEF0A14DC6DB90297" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_C372158D6C97B01101B114DC6DB95C8A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_C372158D6C97B01101B114DC6DB95C8A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_Governmentbondsownedandsoldshortnet" xlink:label="loc_agnc_Governmentbondsownedandsoldshortnet_10F8CFD938E7768255AA14DC6DB90C1E" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_8314B9A31DFEEF8A98BB14DC6DB9A539" xlink:to="loc_agnc_Governmentbondsownedandsoldshortnet_10F8CFD938E7768255AA14DC6DB90C1E" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_C1C9B322C5DF141FB3865EB7A7E96044" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_DerivativeByNatureAxis_C1C9B322C5DF141FB3865EB7A7E96044" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_B0CDAB48601784ECE0295EB7A7E904B4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_C1C9B322C5DF141FB3865EB7A7E96044" xlink:to="loc_us-gaap_DerivativeNameDomain_B0CDAB48601784ECE0295EB7A7E904B4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_B0CDAB48601784ECE0295EB7A7E904B4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_C1C9B322C5DF141FB3865EB7A7E96044" xlink:to="loc_us-gaap_DerivativeNameDomain_B0CDAB48601784ECE0295EB7A7E904B4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_A6CB2726F531A949B2775EB7A7E9618C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B0CDAB48601784ECE0295EB7A7E904B4" xlink:to="loc_us-gaap_FutureMember_A6CB2726F531A949B2775EB7A7E9618C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_EB5ED8A9C8817A74467E5EB7A7E95285" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_EB5ED8A9C8817A74467E5EB7A7E95285" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_EB5ED8A9C8817A74467E5EB7A7E95285" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_EB5ED8A9C8817A74467E5EB7A7E95285" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_5A93ED2DA0EC858B33615EB7A7E95405" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_5A93ED2DA0EC858B33615EB7A7E95405" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_5E9B896E5381A4732BB55EB7A7E9AB7D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:to="loc_us-gaap_InterestRateSwaptionMember_5E9B896E5381A4732BB55EB7A7E9AB7D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_D6065F7371BEDEEFBF975EB7A7E9967C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:to="loc_us-gaap_InterestRateSwapMember_D6065F7371BEDEEFBF975EB7A7E9967C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_2B8C168C18D4A24AF6905EB7A7EF69A6" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:to="loc_us-gaap_FutureMember_2B8C168C18D4A24AF6905EB7A7EF69A6" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_D706AD5F6F5F510A331D5EB7A7EFB2A2" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_612A4696C51100B2E9295EB7A7E9B464" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_D706AD5F6F5F510A331D5EB7A7EFB2A2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_E4C06AE45915D8B9D3E55EB7A7EF7157" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_E4C06AE45915D8B9D3E55EB7A7EF7157" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_B6389B460343E5C56A795EB7A7EF3F17_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E4C06AE45915D8B9D3E55EB7A7EF7157" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_B6389B460343E5C56A795EB7A7EF3F17_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_B6389B460343E5C56A795EB7A7EF3F17" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E4C06AE45915D8B9D3E55EB7A7EF7157" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_B6389B460343E5C56A795EB7A7EF3F17" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_7D3C81E18CFAB708A0FB5EB7A7EF0F44" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_B6389B460343E5C56A795EB7A7EF3F17" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_7D3C81E18CFAB708A0FB5EB7A7EF0F44" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D658EC360058B7E46A1B5EB7A7EF6D27" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D658EC360058B7E46A1B5EB7A7EF6D27" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_F254481F4BF2A08468635EB7A7EF2BBC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D658EC360058B7E46A1B5EB7A7EF6D27" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_F254481F4BF2A08468635EB7A7EF2BBC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_F254481F4BF2A08468635EB7A7EF2BBC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D658EC360058B7E46A1B5EB7A7EF6D27" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_F254481F4BF2A08468635EB7A7EF2BBC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_402C8593F428F258F1CE5EB7A7EF48ED" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_F254481F4BF2A08468635EB7A7EF2BBC" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_402C8593F428F258F1CE5EB7A7EF48ED" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_F7024A224F69D5D1324A5EB7A7EF0B29" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_F7024A224F69D5D1324A5EB7A7EF0B29" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_F7024A224F69D5D1324A5EB7A7EF0B29" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_F7024A224F69D5D1324A5EB7A7EF0B29" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_DA11DA6F253CFDDA135D5EB7A7EF8B54" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_DA11DA6F253CFDDA135D5EB7A7EF8B54" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_39534436013970C460AB5EB7A7EF8812" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_A1539FA568489832AD065EB7A7EF24A7" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_39534436013970C460AB5EB7A7EF8812" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_A0D787EF8606667774645EB7A7EFBA28" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_A0D787EF8606667774645EB7A7EFBA28" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_A0D787EF8606667774645EB7A7EFBA28" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_A0D787EF8606667774645EB7A7EFBA28" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OtherDerivativesMember" xlink:label="loc_agnc_OtherDerivativesMember_0D85B7E64F81B4913F8A5EB7A7EF31B2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_agnc_OtherDerivativesMember_0D85B7E64F81B4913F8A5EB7A7EF31B2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_BFBF422DCD620AA461B05EB7A7F0E6FE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_us-gaap_InterestRateSwapMember_BFBF422DCD620AA461B05EB7A7F0E6FE" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_6FD3990DFF3CF396FD025EB7A7F0DF7D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_6FD3990DFF3CF396FD025EB7A7F0DF7D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_0C3B1D6B8DEB4747FA585EB7A7F5EE06" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_us-gaap_FutureMember_0C3B1D6B8DEB4747FA585EB7A7F5EE06" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember_263F7DFECCF7832964DF5EB7A7F558DC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember_263F7DFECCF7832964DF5EB7A7F558DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_1350DF498F7A13D9995D5EB7A7F573DF" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_DCF41366CB469C13CFCC5EB7A7EF2ADB" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_1350DF498F7A13D9995D5EB7A7F573DF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_F0321E7111E309D7F4125EB7A7F56AF6" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_4E14111656F0F40FC2F25EB7A7E99555" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_F0321E7111E309D7F4125EB7A7F56AF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0AA3AA8657739D953DF75EB7A7F55A8E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_F0321E7111E309D7F4125EB7A7F56AF6" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0AA3AA8657739D953DF75EB7A7F55A8E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0AA3AA8657739D953DF75EB7A7F55A8E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_F0321E7111E309D7F4125EB7A7F56AF6" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0AA3AA8657739D953DF75EB7A7F55A8E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_F8D578EC971739FC35245EB7A7F57F03" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0AA3AA8657739D953DF75EB7A7F55A8E" xlink:to="loc_us-gaap_InterestRateSwapMember_F8D578EC971739FC35245EB7A7F57F03" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TransfersBetweenHierarchyLevels" xlink:label="loc_agnc_TransfersBetweenHierarchyLevels_9DB64733CD6033435C455EB7A7F508A5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_agnc_TransfersBetweenHierarchyLevels_9DB64733CD6033435C455EB7A7F508A5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue_38134F2F16F7D152CB775EB7A7F55CF6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue_38134F2F16F7D152CB775EB7A7F55CF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets" xlink:label="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_2311EC850B45762255BA5EB7A7F503F3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_2311EC850B45762255BA5EB7A7F503F3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NonAgencySecuritiesatFairValue" xlink:label="loc_agnc_NonAgencySecuritiesatFairValue_AD4B8EF84D01029D5F535EB7A7F57EB7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_agnc_NonAgencySecuritiesatFairValue_AD4B8EF84D01029D5F535EB7A7F57EB7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_A65B87D939F6082794F85EB7A7F5BB51" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_A65B87D939F6082794F85EB7A7F5BB51" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_C325BF530455492635395EB7A7F6477C" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_DerivativeAssets_C325BF530455492635395EB7A7F6477C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaap_DerivativeLiabilities_7F5321D341C07DB37F785EB7A7F61FF4" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_DerivativeLiabilities_7F5321D341C07DB37F785EB7A7F61FF4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_E7F1DBF808668B2A85665EB7A7F6B44D" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_E7F1DBF808668B2A85665EB7A7F6B44D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:label="loc_us-gaap_OtherLongTermDebt_3C0A6D45BD15D9F2D1EB5EB7A7F6ED68" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_OtherLongTermDebt_3C0A6D45BD15D9F2D1EB5EB7A7F6ED68" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue" xlink:label="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_4F190D096F362F8A5E765EB7A7F61703" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_4F190D096F362F8A5E765EB7A7F61703" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_534A392EBA12FC7A17EB5EB7A7F6F977" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_534A392EBA12FC7A17EB5EB7A7F6F977" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MarketableSecuritiesEquitySecurities" xlink:label="loc_us-gaap_MarketableSecuritiesEquitySecurities_5E03029F4BA3E10F99425EB7A7F6D319" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_MarketableSecuritiesEquitySecurities_5E03029F4BA3E10F99425EB7A7F6D319" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_FC579A92A2EE7991F03C5EB7A7FB0157" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_07873A6DD4B784544E015EB7A7F580CD" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_FC579A92A2EE7991F03C5EB7A7FB0157" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecurities" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfInvestmentsLineItems" xlink:label="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="loc_us-gaap_ScheduleOfInvestmentsTable_61B6F5B5175DC4EAC56662B5C444297E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_ScheduleOfInvestmentsTable_61B6F5B5175DC4EAC56662B5C444297E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_B325EB3D3F668534FDB662B5C444B2BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_61B6F5B5175DC4EAC56662B5C444297E" xlink:to="loc_us-gaap_InvestmentTypeAxis_B325EB3D3F668534FDB662B5C444B2BD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_B325EB3D3F668534FDB662B5C444B2BD" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_B325EB3D3F668534FDB662B5C444B2BD" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember" xlink:label="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_9C3662372B11A98FF93062B5C445D0D0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:to="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_9C3662372B11A98FF93062B5C445D0D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_EDC2DB948E46C302E75462B5C445E011" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_EDC2DB948E46C302E75462B5C445E011" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember" xlink:label="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_B7D00F9396A0E247631A62B5C4456C78" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:to="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_B7D00F9396A0E247631A62B5C4456C78" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_99785B4A42340554789562B5C445F914" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_74CCA2E5FF59BCD36C7062B5C444CC35" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_99785B4A42340554789562B5C445F914" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EligibleItemOrGroupForFairValueOptionAxis" xlink:label="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_7C75B292087E3B97FC2462B5C445BC9B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_61B6F5B5175DC4EAC56662B5C444297E" xlink:to="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_7C75B292087E3B97FC2462B5C445BC9B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueOptionEligibleItemOrGroupDomain" xlink:label="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_7C75B292087E3B97FC2462B5C445BC9B" xlink:to="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueOptionEligibleItemOrGroupDomain" xlink:label="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_7C75B292087E3B97FC2462B5C445BC9B" xlink:to="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_B84B3243B1B41ECAF17A62B5C44507A8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_B84B3243B1B41ECAF17A62B5C44507A8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember" xlink:label="loc_agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember_38D9852842289CCC026462B5C445356A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_3B5E42BF7D5C413A1D9C62B5C445E5BE" xlink:to="loc_agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember_38D9852842289CCC026462B5C445356A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesPar" xlink:label="loc_agnc_AvailableForSaleSecuritiesPar_39A160FB8471C681247A62B5C44520AD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_AvailableForSaleSecuritiesPar_39A160FB8471C681247A62B5C44520AD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_6C7B21594FB5A05365A962B5C445796B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_6C7B21594FB5A05365A962B5C445796B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnamortizedPremium" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium_87123F64F3415D75215562B5C445A62C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedPremium_87123F64F3415D75215562B5C445A62C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_361BD9CF6599806D9D8162B5C445C988" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_361BD9CF6599806D9D8162B5C445C988" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains_97E046CE8E7ADA0CE70F62B5C445C868" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains_97E046CE8E7ADA0CE70F62B5C445C868" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss_F44377F7B2681165026F62B5C4451D9A" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss_F44377F7B2681165026F62B5C4451D9A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_3EF3A16F01D60976B05C62B5C445851F" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_3EF3A16F01D60976B05C62B5C445851F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestRateDerivativeAssetsAtAmortizedCost" xlink:label="loc_agnc_InterestRateDerivativeAssetsAtAmortizedCost_7E9F881BB86A154C174662B5C4453F46" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_InterestRateDerivativeAssetsAtAmortizedCost_7E9F881BB86A154C174662B5C4453F46" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnrealizedGainOnDerivatives" xlink:label="loc_agnc_UnrealizedGainOnDerivatives_4BDF394F6A9CA81F9D6962B5C4453E70" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_UnrealizedGainOnDerivatives_4BDF394F6A9CA81F9D6962B5C4453E70" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnrealizedLossOnDerivatives" xlink:label="loc_agnc_UnrealizedLossOnDerivatives_E55B014CAB34CB41B5ED62B5C4457072" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_UnrealizedLossOnDerivatives_E55B014CAB34CB41B5ED62B5C4457072" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateDerivativeAssetsAtFairValue" xlink:label="loc_us-gaap_InterestRateDerivativeAssetsAtFairValue_50BF39BC8DDC784EDD2562B5C445AA71" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_InterestRateDerivativeAssetsAtFairValue_50BF39BC8DDC784EDD2562B5C445AA71" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TotalAgencySecurities" xlink:label="loc_agnc_TotalAgencySecurities_6B43CB31C3BAA19563E562B5C445DCF4" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_TotalAgencySecurities_6B43CB31C3BAA19563E562B5C445DCF4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure" xlink:label="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_AF71F14687A00495688462B5C44504DB" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_AF71F14687A00495688462B5C44504DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_B568AE6341BCDCC5535F62B5C445FBE1" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_B568AE6341BCDCC5535F62B5C445FBE1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_WeightedAverageYieldPercentage" xlink:label="loc_agnc_WeightedAverageYieldPercentage_CD70B96BB0DCFA924B6162B5C44578B7" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_WeightedAverageYieldPercentage_CD70B96BB0DCFA924B6162B5C44578B7" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips" xlink:label="loc_agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips_03DED2FD34BB220BA19962B5C4464664" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips_03DED2FD34BB220BA19962B5C4464664" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips" xlink:label="loc_agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips_ACBBBB5CBEB7F6B7796E62B5C446EAAA" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips_ACBBBB5CBEB7F6B7796E62B5C446EAAA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips" xlink:label="loc_agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips_07A7C32D6D5E9741EF0A62B5C446C8AA" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips_07A7C32D6D5E9741EF0A62B5C446C8AA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio" xlink:label="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_A075E1D22EA553B1B71F62B5C44609C8" xlink:type="locator" />
    <definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_A075E1D22EA553B1B71F62B5C44609C8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NonAgencySecuritiesUnrealizedGain" xlink:label="loc_agnc_NonAgencySecuritiesUnrealizedGain_04D6D469421DA193346662B5C446FC22" xlink:type="locator" />
    <definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_NonAgencySecuritiesUnrealizedGain_04D6D469421DA193346662B5C446FC22" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NonAgencySecuritiesUnrealizedLoss" xlink:label="loc_agnc_NonAgencySecuritiesUnrealizedLoss_F5C7E09EE70656F41D3662B5C446507D" xlink:type="locator" />
    <definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_NonAgencySecuritiesUnrealizedLoss_F5C7E09EE70656F41D3662B5C446507D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecuritiesOther" xlink:label="loc_us-gaap_TradingSecuritiesOther_DCEE38D68FD674FB67A862B5C446E16C" xlink:type="locator" />
    <definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_us-gaap_TradingSecuritiesOther_DCEE38D68FD674FB67A862B5C446E16C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesAmortizedCost" xlink:label="loc_agnc_MortgageBackedSecuritiesAmortizedCost_778F48218FCBBFA1BCE162B5C44617FA" xlink:type="locator" />
    <definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_MortgageBackedSecuritiesAmortizedCost_778F48218FCBBFA1BCE162B5C44617FA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesUnrealizedGain" xlink:label="loc_agnc_MortgageBackedSecuritiesUnrealizedGain_6C9605475B466C011B7F62B5C446A7CF" xlink:type="locator" />
    <definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_MortgageBackedSecuritiesUnrealizedGain_6C9605475B466C011B7F62B5C446A7CF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesUnrealizedLoss" xlink:label="loc_agnc_MortgageBackedSecuritiesUnrealizedLoss_33D47DDD0198902E252262B5C4468887" xlink:type="locator" />
    <definitionArc order="25" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_2C70E619A86079DC5F7662B5C4459B57" xlink:to="loc_agnc_MortgageBackedSecuritiesUnrealizedLoss_33D47DDD0198902E252262B5C4468887" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_80A13AE54DA5AF3448F062C05394F20F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_80A13AE54DA5AF3448F062C05394F20F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_929485288F99ADA49AA362C05394B054" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_80A13AE54DA5AF3448F062C05394F20F" xlink:to="loc_us-gaap_DerivativeByNatureAxis_929485288F99ADA49AA362C05394B054" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_06BAAB8A28B21A54CF2462C0539497ED_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_929485288F99ADA49AA362C05394B054" xlink:to="loc_us-gaap_DerivativeNameDomain_06BAAB8A28B21A54CF2462C0539497ED_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_06BAAB8A28B21A54CF2462C0539497ED" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_929485288F99ADA49AA362C05394B054" xlink:to="loc_us-gaap_DerivativeNameDomain_06BAAB8A28B21A54CF2462C0539497ED" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember" xlink:label="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_EB18EC33D3B039A592D262C05394B7CF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_06BAAB8A28B21A54CF2462C0539497ED" xlink:to="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_EB18EC33D3B039A592D262C05394B7CF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_38CE8B41B4B540E6993262C053947ABF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_80A13AE54DA5AF3448F062C05394F20F" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_38CE8B41B4B540E6993262C053947ABF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_417212F1A1B30696AB4D62C053948A60_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_38CE8B41B4B540E6993262C053947ABF" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_417212F1A1B30696AB4D62C053948A60_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_417212F1A1B30696AB4D62C053948A60" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_38CE8B41B4B540E6993262C053947ABF" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_417212F1A1B30696AB4D62C053948A60" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_DB2CEDB1B0A98AF03ED562C053949EF9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_417212F1A1B30696AB4D62C053948A60" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_DB2CEDB1B0A98AF03ED562C053949EF9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_20878389869A49DF07CE62C0539406C6" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_80A13AE54DA5AF3448F062C05394F20F" xlink:to="loc_us-gaap_InvestmentTypeAxis_20878389869A49DF07CE62C0539406C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_BAFDE6C38B14153E6BDC62C05394313A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_20878389869A49DF07CE62C0539406C6" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_BAFDE6C38B14153E6BDC62C05394313A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_BAFDE6C38B14153E6BDC62C05394313A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_20878389869A49DF07CE62C0539406C6" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_BAFDE6C38B14153E6BDC62C05394313A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_1EFE8660BD8524D0CEA862C05394FECE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_BAFDE6C38B14153E6BDC62C05394313A" xlink:to="loc_us-gaap_AgencySecuritiesMember_1EFE8660BD8524D0CEA862C05394FECE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure" xlink:label="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_ABD57CAC717550EFF23D62C053941C15" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_ABD57CAC717550EFF23D62C053941C15" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_A4BDAC21AEFC7976683762C05394E7D1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_A4BDAC21AEFC7976683762C05394E7D1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_45A29A8FA0BF37398DCE62C053947A78" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_45A29A8FA0BF37398DCE62C053947A78" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_C4F1D367097DD9AEF7A262C05394ADDF" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_C4F1D367097DD9AEF7A262C05394ADDF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio" xlink:label="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_468C62AB46BACB3092BC62C0539482E1" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_468C62AB46BACB3092BC62C0539482E1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_WeightedAverageLifeInterestOnlySecurities" xlink:label="loc_agnc_WeightedAverageLifeInterestOnlySecurities_D6AD9C72C976B5C478A162C05394F628" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_WeightedAverageLifeInterestOnlySecurities_D6AD9C72C976B5C478A162C05394F628" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_WeightedAverageLifePrincipalOnlySecurities" xlink:label="loc_agnc_WeightedAverageLifePrincipalOnlySecurities_19C9C422C7413B419B4862C053945747" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_WeightedAverageLifePrincipalOnlySecurities_19C9C422C7413B419B4862C053945747" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_C6D1833B85C0E9E2D11B62C053949E83" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_C6D1833B85C0E9E2D11B62C053949E83" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecuritiesHeldAsCollateralAtFairValue" xlink:label="loc_us-gaap_SecuritiesHeldAsCollateralAtFairValue_6BC7292030158276132462C05394DE34" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_SecuritiesHeldAsCollateralAtFairValue_6BC7292030158276132462C05394DE34" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:label="loc_us-gaap_OtherLongTermDebt_6BBB9F18E569AE7054D962C05394E78C" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_OtherLongTermDebt_6BBB9F18E569AE7054D962C05394E78C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral" xlink:label="loc_agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral_AA1755B264F81D22074662C053942C5E" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral_AA1755B264F81D22074662C053942C5E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_8511E34D29D6EE7E191062C0539492BD" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_8511E34D29D6EE7E191062C0539492BD" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GainLossOnOtherDebt" xlink:label="loc_agnc_GainLossOnOtherDebt_E8309719747F51D682E962C05394ECCA" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_GainLossOnOtherDebt_E8309719747F51D682E962C05394ECCA" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FairValueOfCmoSecuritiesDirectlyHeld" xlink:label="loc_agnc_FairValueOfCmoSecuritiesDirectlyHeld_2E3EB900BB0D628508AB62C05395A25C" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_FairValueOfCmoSecuritiesDirectlyHeld_2E3EB900BB0D628508AB62C05395A25C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_SecuritizedCmoSecurities" xlink:label="loc_agnc_SecuritizedCmoSecurities_79FBBBA01EE81982BE8162C053959424" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_SecuritizedCmoSecurities_79FBBBA01EE81982BE8162C053959424" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure" xlink:label="loc_agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure_28DBA235DB33CFEC452162C053956A4C" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_F5EEA1623DCFDA9920A362C0539467E6" xlink:to="loc_agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure_28DBA235DB33CFEC452162C053956A4C" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_85629C2A30F8BBAC17A414DC6DCD8BBD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_85629C2A30F8BBAC17A414DC6DCD8BBD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_019F9938230CC2F6466814DC6DCDBDA9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_85629C2A30F8BBAC17A414DC6DCD8BBD" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_019F9938230CC2F6466814DC6DCDBDA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_019F9938230CC2F6466814DC6DCDBDA9" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_019F9938230CC2F6466814DC6DCDBDA9" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_CC9026B02CAF196E06DE14DC6DCD7000" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_CC9026B02CAF196E06DE14DC6DCD7000" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember" xlink:label="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_0B30D5DB53B81AB045D414DC6DCD19EF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:to="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_0B30D5DB53B81AB045D414DC6DCD19EF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanFiveYearsMember" xlink:label="loc_agnc_GreaterThanFiveYearsMember_BAB05836B30177F474C614DC6DCDBC0E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:to="loc_agnc_GreaterThanFiveYearsMember_BAB05836B30177F474C614DC6DCDBC0E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GreaterThanTenYearsMember" xlink:label="loc_agnc_GreaterThanTenYearsMember_8EF9620C85B47011BFDD14DC6DCDDD5E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_8E19D11A6E2BD3BB511014DC6DCDE346" xlink:to="loc_agnc_GreaterThanTenYearsMember_8EF9620C85B47011BFDD14DC6DCDDD5E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue_DB89455BD5E4D76AB98614DC6DCDE55A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue_DB89455BD5E4D76AB98614DC6DCDE55A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost_3D1A1F81800C8D97ADE414DC6DCD82F3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost_3D1A1F81800C8D97ADE414DC6DCD82F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_FFCB390D6BF3BCD4575C14DC6DCD0AA8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_us-gaap_AvailableForSaleSecurities_FFCB390D6BF3BCD4575C14DC6DCD0AA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_5DD9B4461BD9A492048614DC6DCD89A6" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_5DD9B4461BD9A492048614DC6DCD89A6" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate_237BACB412B0663401EC14DC6DCDC90F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate_237BACB412B0663401EC14DC6DCDC90F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield_AC1DC804E62E5B46E27914DC6DCD1FEB" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_B8357936842650D333B814DC6DCDE065" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield_AC1DC804E62E5B46E27914DC6DCD1FEB" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0DDD4D181A9B3ADFCB9614DC6BF89893" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8959CC27D69551C6E06614DC6BF829B9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0DDD4D181A9B3ADFCB9614DC6BF89893" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8959CC27D69551C6E06614DC6BF829B9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29702F0EEDD3CA6DCAD614DC6BF82F09" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8959CC27D69551C6E06614DC6BF829B9" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29702F0EEDD3CA6DCAD614DC6BF82F09" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_66C41C3C472E9C2073DD14DC6BF88D72_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29702F0EEDD3CA6DCAD614DC6BF82F09" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_66C41C3C472E9C2073DD14DC6BF88D72_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_66C41C3C472E9C2073DD14DC6BF88D72" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29702F0EEDD3CA6DCAD614DC6BF82F09" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_66C41C3C472E9C2073DD14DC6BF88D72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_452C146B732C52F5E19C14DC6BF82738" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_66C41C3C472E9C2073DD14DC6BF88D72" xlink:to="loc_us-gaap_AgencySecuritiesMember_452C146B732C52F5E19C14DC6BF82738" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AccumulatedOtherComprehensiveIncomeLossRollForward" xlink:label="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_6AAD3752DC238644757E14DC6BF8FE9E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0DDD4D181A9B3ADFCB9614DC6BF89893" xlink:to="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_6AAD3752DC238644757E14DC6BF8FE9E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_78F60661D5C5E008459314DC6BF8CCA6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_6AAD3752DC238644757E14DC6BF8FE9E" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_78F60661D5C5E008459314DC6BF8CCA6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_398ED0DA5B33C93C31E814DC6BF82529" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_6AAD3752DC238644757E14DC6BF8FE9E" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_398ED0DA5B33C93C31E814DC6BF82529" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization" xlink:label="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_ABDE568A9C832E4EE08114DC6BF8BCD5" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_6AAD3752DC238644757E14DC6BF8FE9E" xlink:to="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_ABDE568A9C832E4EE08114DC6BF8BCD5" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_D858A8ABC382DFE81FF914DC6A2CA765" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_StatementTable_D858A8ABC382DFE81FF914DC6A2CA765" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6995BD57E24BA2053F1214DC6A2CA6F5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_D858A8ABC382DFE81FF914DC6A2CA765" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6995BD57E24BA2053F1214DC6A2CA6F5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_C8FBDED470BEBFF7859314DC6A2C9099_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6995BD57E24BA2053F1214DC6A2CA6F5" xlink:to="loc_us-gaap_EquityComponentDomain_C8FBDED470BEBFF7859314DC6A2C9099_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_C8FBDED470BEBFF7859314DC6A2C9099" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6995BD57E24BA2053F1214DC6A2CA6F5" xlink:to="loc_us-gaap_EquityComponentDomain_C8FBDED470BEBFF7859314DC6A2C9099" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_858CCD762155550C5FA714DC6A2C3E78" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_C8FBDED470BEBFF7859314DC6A2C9099" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_858CCD762155550C5FA714DC6A2C3E78" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_36C5F3B4F884A8DDE12414DC6A2C2A0A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_36C5F3B4F884A8DDE12414DC6A2C2A0A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_2BABD37594F1C623FE2F14DC6A2CDCFC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_2BABD37594F1C623FE2F14DC6A2CDCFC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_B5181405678DD6946A8514DC6A2C21FE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_B5181405678DD6946A8514DC6A2C21FE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_B2A484B40FDDB5E6246114DC6A2C8665" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_B2A484B40FDDB5E6246114DC6A2C8665" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_F3E952AA497FD19BB10314DC6A2C3931" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_F3E952AA497FD19BB10314DC6A2C3931" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_D442870DB67165E4924A14DC6A2C897E" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_47CA7B0FEE7700FF4A0914DC6A2C71D7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_D442870DB67165E4924A14DC6A2C897E" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_30F9F0C312BB02F85DC562B5D129EADF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_30F9F0C312BB02F85DC562B5D129EADF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_A4929C1A1F3AB8CB40B162B5D129BFFD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_30F9F0C312BB02F85DC562B5D129EADF" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_A4929C1A1F3AB8CB40B162B5D129BFFD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_A4929C1A1F3AB8CB40B162B5D129BFFD" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_A4929C1A1F3AB8CB40B162B5D129BFFD" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:label="loc_us-gaap_FixedIncomeSecuritiesMember_DD99B0DBF98D89D13CED62B5D1293327" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:to="loc_us-gaap_FixedIncomeSecuritiesMember_DD99B0DBF98D89D13CED62B5D1293327" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AdjustableRateMember" xlink:label="loc_agnc_AdjustableRateMember_F9F38F2EDDB7915DA21F62B5D1296506" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:to="loc_agnc_AdjustableRateMember_F9F38F2EDDB7915DA21F62B5D1296506" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CollateralizedMortgageObligationsMember" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_3B379496FA20EAF0E7B962B5D1296045" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_3B379496FA20EAF0E7B962B5D1296045" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_0072C2FE1BFC5B23AB7362B5D129C010" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_512F6AC40FAEA225C5DC62B5D129CAAB" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_0072C2FE1BFC5B23AB7362B5D129C010" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_E0EE565795A6FF2D3ECC62B5D1291586" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_30F9F0C312BB02F85DC562B5D129EADF" xlink:to="loc_us-gaap_InvestmentTypeAxis_E0EE565795A6FF2D3ECC62B5D1291586" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_E0EE565795A6FF2D3ECC62B5D1291586" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_E0EE565795A6FF2D3ECC62B5D1291586" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_6B736881EC643E7CD0DB62B5D129E85A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81" xlink:to="loc_us-gaap_AgencySecuritiesMember_6B736881EC643E7CD0DB62B5D129E85A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_DD2E3B4FA3E64D75C7E662B5D12903B1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_528C52C33A4B9F056F9062B5D129DA81" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_DD2E3B4FA3E64D75C7E662B5D12903B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_0D21AB0B58B04D8375F862B5D129AA84" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_0D21AB0B58B04D8375F862B5D129AA84" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NonAgencySecuritiesUnrealizedGain" xlink:label="loc_agnc_NonAgencySecuritiesUnrealizedGain_9539E483F23E14A585C662B5D1296E72" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_NonAgencySecuritiesUnrealizedGain_9539E483F23E14A585C662B5D1296E72" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NonAgencySecuritiesUnrealizedLoss" xlink:label="loc_agnc_NonAgencySecuritiesUnrealizedLoss_59BE1F67DFF8FE48985C62B5D1296156" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_NonAgencySecuritiesUnrealizedLoss_59BE1F67DFF8FE48985C62B5D1296156" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesAmortizedCost" xlink:label="loc_agnc_MortgageBackedSecuritiesAmortizedCost_C2F2F1AE1339A72A2F3762B5D129FB20" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_MortgageBackedSecuritiesAmortizedCost_C2F2F1AE1339A72A2F3762B5D129FB20" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesUnrealizedGain" xlink:label="loc_agnc_MortgageBackedSecuritiesUnrealizedGain_21F21743B82439F15D4B62B5D1295D69" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_MortgageBackedSecuritiesUnrealizedGain_21F21743B82439F15D4B62B5D1295D69" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_MortgageBackedSecuritiesUnrealizedLoss" xlink:label="loc_agnc_MortgageBackedSecuritiesUnrealizedLoss_40EC28235A407283CC1C62B5D12915FD" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_MortgageBackedSecuritiesUnrealizedLoss_40EC28235A407283CC1C62B5D12915FD" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesGrossUnrealizedGain" xlink:label="loc_agnc_AgencySecuritiesGrossUnrealizedGain_EB8937BBC91E2F572B2562B5D129EC21" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_AgencySecuritiesGrossUnrealizedGain_EB8937BBC91E2F572B2562B5D129EC21" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesGrossUnrealizedLoss" xlink:label="loc_agnc_AgencySecuritiesGrossUnrealizedLoss_B3B35B6C306F2CA716D562B5D1290F9B" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_AgencySecuritiesGrossUnrealizedLoss_B3B35B6C306F2CA716D562B5D1290F9B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_5A5BAF90815069AA398962B5D12983B4" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_AvailableForSaleSecurities_5A5BAF90815069AA398962B5D12983B4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecuritiesCost" xlink:label="loc_us-gaap_TradingSecuritiesCost_572A5D3BD80CC4F131B362B5D12986E0" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_TradingSecuritiesCost_572A5D3BD80CC4F131B362B5D12986E0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradingSecuritiesOther" xlink:label="loc_us-gaap_TradingSecuritiesOther_29F88ACB30BDB6F0237162B5D129D425" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_TradingSecuritiesOther_29F88ACB30BDB6F0237162B5D129D425" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesAmortizedCost" xlink:label="loc_agnc_AgencySecuritiesAmortizedCost_B1E626F65D548EBBA2A862B5D12A2E7D" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_AgencySecuritiesAmortizedCost_B1E626F65D548EBBA2A862B5D12A2E7D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TotalAgencySecurities" xlink:label="loc_agnc_TotalAgencySecurities_AB2597E003B5060A4DDC62B5D12A780D" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_agnc_TotalAgencySecurities_AB2597E003B5060A4DDC62B5D12A780D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure" xlink:label="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_1D69A80CBFC78EBF277C62B5D12A269B" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E5E29EC33B9957AE65AE62B5D12911C6" xlink:to="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_1D69A80CBFC78EBF277C62B5D12A269B" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_4DACB977F88FC7D7FFCD5EB7AB33BAC2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_4DACB977F88FC7D7FFCD5EB7AB33BAC2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_821C5B84C03D94B743EB5EB7AB336B9B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_4DACB977F88FC7D7FFCD5EB7AB33BAC2" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_821C5B84C03D94B743EB5EB7AB336B9B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_37AB0F639DC723B730D45EB7AB39DAB8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_821C5B84C03D94B743EB5EB7AB336B9B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_37AB0F639DC723B730D45EB7AB39DAB8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_37AB0F639DC723B730D45EB7AB39DAB8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_821C5B84C03D94B743EB5EB7AB336B9B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_37AB0F639DC723B730D45EB7AB39DAB8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_815AC67A22C69F1178A35EB7AB39892C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_37AB0F639DC723B730D45EB7AB39DAB8" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_815AC67A22C69F1178A35EB7AB39892C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnderlyingAssetClassAxis" xlink:label="loc_us-gaap_UnderlyingAssetClassAxis_05444551589A7532092E5EB7AB3976BD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_4DACB977F88FC7D7FFCD5EB7AB33BAC2" xlink:to="loc_us-gaap_UnderlyingAssetClassAxis_05444551589A7532092E5EB7AB3976BD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_08A2E25048CCDD4AA9EB5EB7AB39EC61_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_05444551589A7532092E5EB7AB3976BD" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_08A2E25048CCDD4AA9EB5EB7AB39EC61_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_08A2E25048CCDD4AA9EB5EB7AB39EC61" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_05444551589A7532092E5EB7AB3976BD" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_08A2E25048CCDD4AA9EB5EB7AB39EC61" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_FA1B7DB5C883475452405EB7AB3934C0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_08A2E25048CCDD4AA9EB5EB7AB39EC61" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_FA1B7DB5C883475452405EB7AB3934C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_6DBBB51848EB520970925EB7AB396FE6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_6DBBB51848EB520970925EB7AB396FE6" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_CostOfSaleOfAvailableForSaleSecuities" xlink:label="loc_agnc_CostOfSaleOfAvailableForSaleSecuities_45462CA5C7E63CD6EA6A5EB7AB3AA68F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_agnc_CostOfSaleOfAvailableForSaleSecuities_45462CA5C7E63CD6EA6A5EB7AB3AA68F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities_78E1285D707F48D33B6E5EB7AB3A7776" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities_78E1285D707F48D33B6E5EB7AB3A7776" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS" xlink:label="loc_us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS_ECB85EE374EF4D06B2985EB7AB3B4A32" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS_ECB85EE374EF4D06B2985EB7AB3B4A32" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MarketableSecuritiesRealizedGainLoss" xlink:label="loc_us-gaap_MarketableSecuritiesRealizedGainLoss_A4CEC44E9114A9A94EB45EB7AB3BEE84" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_MarketableSecuritiesRealizedGainLoss_A4CEC44E9114A9A94EB45EB7AB3BEE84" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses_8B934FAA8C5C25B049815EB7AB3B5D67" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_808DF5F6DBDA598F0F655EB7AB39C5CC" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses_8B934FAA8C5C25B049815EB7AB3B5D67" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/Organization" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/OrganizationDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:type="extended">
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:type="locator" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_BF808A40C1243D77D2607CD3D56E6EA0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_BF808A40C1243D77D2607CD3D56E6EA0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_01EA90B9E5D130E32CA07CD3D56E518A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_BF808A40C1243D77D2607CD3D56E6EA0" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_01EA90B9E5D130E32CA07CD3D56E518A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_01EA90B9E5D130E32CA07CD3D56E518A" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_01EA90B9E5D130E32CA07CD3D56E518A" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_0BD6FB43B7845184214D7CD3D56E2875" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_0BD6FB43B7845184214D7CD3D56E2875" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnderPrimeBrokerAgreementsMember" xlink:label="loc_agnc_UnderPrimeBrokerAgreementsMember_98F545AFA3012DA015307CD3D56ED81B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547" xlink:to="loc_agnc_UnderPrimeBrokerAgreementsMember_98F545AFA3012DA015307CD3D56ED81B" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ExcludingCashReceivedMember" xlink:label="loc_agnc_ExcludingCashReceivedMember_1D77CFE133CE9CB5611C7CD3D56EBE2D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_DAD97FAF7D2AE1FE3EA47CD3D56EC547" xlink:to="loc_agnc_ExcludingCashReceivedMember_1D77CFE133CE9CB5611C7CD3D56EBE2D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassAxis" xlink:label="loc_invest_InvestmentSecuritiesClassAxis_6B0E6F9CE670A795A2717CD3D56EFED5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_BF808A40C1243D77D2607CD3D56E6EA0" xlink:to="loc_invest_InvestmentSecuritiesClassAxis_6B0E6F9CE670A795A2717CD3D56EFED5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6B0E6F9CE670A795A2717CD3D56EFED5" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6B0E6F9CE670A795A2717CD3D56EFED5" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_3142FF09BC40E75E4F477CD3D56E157C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_3142FF09BC40E75E4F477CD3D56E157C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_67F04B97BD5DC65D16F67CD3D56E9381" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_67F04B97BD5DC65D16F67CD3D56E9381" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_UnderPrimeBrokerAgreementsMember" xlink:label="loc_agnc_UnderPrimeBrokerAgreementsMember_5998267ABAB54779DF447CD3D56EF76E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_agnc_UnderPrimeBrokerAgreementsMember_5998267ABAB54779DF447CD3D56EF76E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_IncludesSoldButNotYetSettledSecuritiesMember" xlink:label="loc_agnc_IncludesSoldButNotYetSettledSecuritiesMember_667A0BB0AE120E7EC2C07CD3D56FB293" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_agnc_IncludesSoldButNotYetSettledSecuritiesMember_667A0BB0AE120E7EC2C07CD3D56FB293" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AAANonAgencyMortgageBackedSecuritiesMember" xlink:label="loc_agnc_AAANonAgencyMortgageBackedSecuritiesMember_FCCC8B5DA8BFA54F1D387CD3D56F668B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_agnc_AAANonAgencyMortgageBackedSecuritiesMember_FCCC8B5DA8BFA54F1D387CD3D56F668B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_D12FA4DBFB86EA5647667CD3D56F3CD6" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_D12FA4DBFB86EA5647667CD3D56F3CD6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_449D6BA57C791DEA062F7CD3D56F1B1C" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_D0DDB25D8F5A96B209437CD3D56EAA76" xlink:to="loc_us-gaap_DerivativeMember_449D6BA57C791DEA062F7CD3D56F1B1C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_A947EB4A1B3DEE1235C67CD3D56FC7CD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_BF808A40C1243D77D2607CD3D56E6EA0" xlink:to="loc_us-gaap_InvestmentTypeAxis_A947EB4A1B3DEE1235C67CD3D56FC7CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_A947EB4A1B3DEE1235C67CD3D56FC7CD" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_A947EB4A1B3DEE1235C67CD3D56FC7CD" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_132199A2B7D5727EF4877CD3D56FF115" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_132199A2B7D5727EF4877CD3D56FF115" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_7141FCD6064D0503C1D87CD3D56F686B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_C76F85D8504C4676C8C87CD3D56FDB83" xlink:to="loc_us-gaap_DerivativeMember_7141FCD6064D0503C1D87CD3D56F686B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalHomeLoanBankStock" xlink:label="loc_us-gaap_FederalHomeLoanBankStock_0E2D18B4B21538D8AC1C7CD83DCFB726" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_us-gaap_FederalHomeLoanBankStock_0E2D18B4B21538D8AC1C7CD83DCFB726" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_242A939D35FE126645EC7CD3D574140C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_242A939D35FE126645EC7CD3D574140C" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest" xlink:label="loc_agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest_7A7FC632D90E4640A5957CD3D574655B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest_7A7FC632D90E4640A5957CD3D574655B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents_1BA33301C0D50E4F156D7CD3D5743658" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalents_1BA33301C0D50E4F156D7CD3D5743658" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TotalFairValueofSecuritiesPledgedandAccruedInterest" xlink:label="loc_agnc_TotalFairValueofSecuritiesPledgedandAccruedInterest_C6DACB81FD6462FA39847CD3D57446C7" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_agnc_TotalFairValueofSecuritiesPledgedandAccruedInterest_C6DACB81FD6462FA39847CD3D57446C7" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest" xlink:label="loc_agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest_8CDD93CC120C19433A557CD3D5749480" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_DA6B60F83C22A82E2FA97CD3D574FC7D" xlink:to="loc_agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest_8CDD93CC120C19433A557CD3D5749480" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:type="extended">
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:type="locator" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_80B901AF4D8586788D72816A7C61A532" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_80B901AF4D8586788D72816A7C61A532" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_39535F226FB3482028FC816A7C614F23_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_80B901AF4D8586788D72816A7C61A532" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_39535F226FB3482028FC816A7C614F23_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_39535F226FB3482028FC816A7C614F23" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_80B901AF4D8586788D72816A7C61A532" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_39535F226FB3482028FC816A7C614F23" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_425A0C0BF3B26CB41D6B816A7C6180E9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_39535F226FB3482028FC816A7C614F23" xlink:to="loc_us-gaap_DerivativeMember_425A0C0BF3B26CB41D6B816A7C6180E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_4B691FCEFFA204069E42816A7C6105C5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:to="loc_us-gaap_InvestmentTypeAxis_4B691FCEFFA204069E42816A7C6105C5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_A5CAA1E80AEF16D5649E816A7C61B54C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_4B691FCEFFA204069E42816A7C6105C5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_A5CAA1E80AEF16D5649E816A7C61B54C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_A5CAA1E80AEF16D5649E816A7C61B54C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_4B691FCEFFA204069E42816A7C6105C5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_A5CAA1E80AEF16D5649E816A7C61B54C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_B5D6555C0DDD133B9C9A816A7C61CA39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_A5CAA1E80AEF16D5649E816A7C61B54C" xlink:to="loc_us-gaap_DerivativeMember_B5D6555C0DDD133B9C9A816A7C61CA39" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassAxis" xlink:label="loc_invest_InvestmentSecuritiesClassAxis_415CE0A32A2DE6C14B28816A7C6126BB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:to="loc_invest_InvestmentSecuritiesClassAxis_415CE0A32A2DE6C14B28816A7C6126BB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_415CE0A32A2DE6C14B28816A7C6126BB" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_415CE0A32A2DE6C14B28816A7C6126BB" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_D915EB7148FAD0851218816A7C6147E4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B" xlink:to="loc_us-gaap_DerivativeMember_D915EB7148FAD0851218816A7C6147E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_236FE357578458819022816A7C6139BB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_236FE357578458819022816A7C6139BB" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReverseRepurchaseAgreementsMember" xlink:label="loc_agnc_ReverseRepurchaseAgreementsMember_AF34DB1C6FF1EECDD7A6816A7C61A5B3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_3CEB8A6924189898A103816A7C61139B" xlink:to="loc_agnc_ReverseRepurchaseAgreementsMember_AF34DB1C6FF1EECDD7A6816A7C61A5B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtSecurityAxis" xlink:label="loc_us-gaap_DebtSecurityAxis_F7C83999E99FBC80DEA3816A7C61835F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_0D3DCB56D3F3C9447ABD816A7C61C1F7" xlink:to="loc_us-gaap_DebtSecurityAxis_F7C83999E99FBC80DEA3816A7C61835F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_0622D7C3E4AE0A0E2FE2816A7C61DD2D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtSecurityAxis_F7C83999E99FBC80DEA3816A7C61835F" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_0622D7C3E4AE0A0E2FE2816A7C61DD2D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_0622D7C3E4AE0A0E2FE2816A7C61DD2D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtSecurityAxis_F7C83999E99FBC80DEA3816A7C61835F" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_0622D7C3E4AE0A0E2FE2816A7C61DD2D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AssetsPledgedtoUsMember" xlink:label="loc_agnc_AssetsPledgedtoUsMember_D1D93040C116BB1F7AC0816A7C619286" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_0622D7C3E4AE0A0E2FE2816A7C61DD2D" xlink:to="loc_agnc_AssetsPledgedtoUsMember_D1D93040C116BB1F7AC0816A7C619286" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalHomeLoanBankStock" xlink:label="loc_us-gaap_FederalHomeLoanBankStock_D31962431461DD1A1E79816A7C61F108" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:to="loc_us-gaap_FederalHomeLoanBankStock_D31962431461DD1A1E79816A7C61F108" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_831ACFFEF92B74ABBD0F816A7C611D5F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_831ACFFEF92B74ABBD0F816A7C611D5F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue" xlink:label="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_C25EA51B4C1D8C07FE4F816A7C61366F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:to="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_C25EA51B4C1D8C07FE4F816A7C61366F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents_122B17F004CB4D66B9D7816A7C612ACB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_4A0E9BEB421978D49935816A7C616EDF" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalents_122B17F004CB4D66B9D7816A7C612ACB" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsNarrativeDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:type="extended">
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:type="locator" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_521BAAA87204611C87965E1DC9482D30" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_521BAAA87204611C87965E1DC9482D30" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_521BAAA87204611C87965E1DC9482D30" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_521BAAA87204611C87965E1DC9482D30" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ReverseRepurchaseAgreementsMember" xlink:label="loc_agnc_ReverseRepurchaseAgreementsMember_AF04D23250D0ADDD120D5E1DC949A272" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B" xlink:to="loc_agnc_ReverseRepurchaseAgreementsMember_AF04D23250D0ADDD120D5E1DC949A272" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_B00F375F8C55C6A0B5BB5E1DC94982C6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_0933B0AE50116749CD9F5E1DC949C33B" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_B00F375F8C55C6A0B5BB5E1DC94982C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_7A0B0A26CE5A9B54BBCE5E1DC9493062" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_7A0B0A26CE5A9B54BBCE5E1DC9493062" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_7A0B0A26CE5A9B54BBCE5E1DC9493062" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_7A0B0A26CE5A9B54BBCE5E1DC9493062" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsMember" xlink:label="loc_us-gaap_AssetsMember_04D33A74E3A6AF8BC2195E1DC9497F39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F" xlink:to="loc_us-gaap_AssetsMember_04D33A74E3A6AF8BC2195E1DC9497F39" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilityMember" xlink:label="loc_us-gaap_LiabilityMember_FFBC28A4559866D47D7B5E1DC9491812" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_B04B089060A1A4FC52CA5E1DC949697F" xlink:to="loc_us-gaap_LiabilityMember_FFBC28A4559866D47D7B5E1DC9491812" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_BA878282FAF5F19F69065E1DC9492564" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:to="loc_us-gaap_DerivativeByNatureAxis_BA878282FAF5F19F69065E1DC9492564" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_BA878282FAF5F19F69065E1DC9492564" xlink:to="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_BA878282FAF5F19F69065E1DC9492564" xlink:to="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_ED1693461862ADEABA785E1DC949398D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5" xlink:to="loc_us-gaap_InterestRateSwapMember_ED1693461862ADEABA785E1DC949398D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_1CCE8FEB2638CDDC42B35E1DC9497B5B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_E37A8E221C331831CA175E1DC94983B5" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_1CCE8FEB2638CDDC42B35E1DC9497B5B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_2F0430EEE75FEFC055325E1DC949A05D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_83CA7443DDE700466C695E1DC948BA39" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_2F0430EEE75FEFC055325E1DC949A05D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_DF33F1EC0830357426C45E1DC949503D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2F0430EEE75FEFC055325E1DC949A05D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_DF33F1EC0830357426C45E1DC949503D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_DF33F1EC0830357426C45E1DC949503D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2F0430EEE75FEFC055325E1DC949A05D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_DF33F1EC0830357426C45E1DC949503D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SwaptionMember" xlink:label="loc_us-gaap_SwaptionMember_7DF9F430299D035C3E2B5E1DC949E6B0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_DF33F1EC0830357426C45E1DC949503D" xlink:to="loc_us-gaap_SwaptionMember_7DF9F430299D035C3E2B5E1DC949E6B0" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GrossAmountOfRecognizedAssetsLiabilities" xlink:label="loc_agnc_GrossAmountOfRecognizedAssetsLiabilities_58510CB578B6B4A036C95E1DC94A30D9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_GrossAmountOfRecognizedAssetsLiabilities_58510CB578B6B4A036C95E1DC94A30D9" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet" xlink:label="loc_agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_920568DF36F51671CE0C5E1DC94AD392" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_920568DF36F51671CE0C5E1DC94AD392" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet" xlink:label="loc_agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet_6B4062965337A3C472815E1DC94A7BF1" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet_6B4062965337A3C472815E1DC94A7BF1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet" xlink:label="loc_agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet_6A78AA74AF93A44446195E1DC94A0E5D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet_6A78AA74AF93A44446195E1DC94A0E5D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet" xlink:label="loc_agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_0E848B2F4C0BFD3823A65E1DC94A2719" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_F33B03C5B2818B06971E5E1DC949BD75" xlink:to="loc_agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_0E848B2F4C0BFD3823A65E1DC94A2719" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsRepurchaseAgreementsWithCounterpartiesGreaterThanOrEqualTo5OfEquityAtRiskDetails" xlink:type="extended">
    <loc xlink:href="agnc-20160331.xsd#agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems" xlink:label="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems_B60ABB9D95D29BEEBC368159B73B46EC" xlink:type="locator" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskTable" xlink:label="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskTable_C50DEBC84BEF6200A4A68159B73B93BB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems_B60ABB9D95D29BEEBC368159B73B46EC" xlink:to="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskTable_C50DEBC84BEF6200A4A68159B73B93BB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CounterpartyNameAxis" xlink:label="loc_us-gaap_CounterpartyNameAxis_068779C203CF85F1A7C88159B73BFA9D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskTable_C50DEBC84BEF6200A4A68159B73B93BB" xlink:to="loc_us-gaap_CounterpartyNameAxis_068779C203CF85F1A7C88159B73BFA9D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_4A83CE499FF6B7D335168159B73B93BA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CounterpartyNameAxis_068779C203CF85F1A7C88159B73BFA9D" xlink:to="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_4A83CE499FF6B7D335168159B73B93BA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_4A83CE499FF6B7D335168159B73B93BA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CounterpartyNameAxis_068779C203CF85F1A7C88159B73BFA9D" xlink:to="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_4A83CE499FF6B7D335168159B73B93BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_57A13A60C85050B413F28159B73BCD7D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems_B60ABB9D95D29BEEBC368159B73B46EC" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_57A13A60C85050B413F28159B73BCD7D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RiskOfRepurchaseAgreementToStockholdersEquity" xlink:label="loc_agnc_RiskOfRepurchaseAgreementToStockholdersEquity_02CF50A5848BB358B6DF8159B73B7BE6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems_B60ABB9D95D29BEEBC368159B73B46EC" xlink:to="loc_agnc_RiskOfRepurchaseAgreementToStockholdersEquity_02CF50A5848BB358B6DF8159B73B7BE6" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity" xlink:label="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_2B82955E9320DC1B2E9B8159B73BF148" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_RepurchaseAgreementswithCounterpartiesGreaterthanorequalto5ofEquityatRiskLineItems_B60ABB9D95D29BEEBC368159B73B46EC" xlink:to="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_2B82955E9320DC1B2E9B8159B73BF148" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:type="extended">
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:type="locator" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_C47DF07F8AD5990C230F816A7C610975" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_C47DF07F8AD5990C230F816A7C610975" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_14D5A0344B10647E4D7D816A7C615FA9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_C47DF07F8AD5990C230F816A7C610975" xlink:to="loc_us-gaap_InvestmentTypeAxis_14D5A0344B10647E4D7D816A7C615FA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_14D5A0344B10647E4D7D816A7C615FA9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_14D5A0344B10647E4D7D816A7C615FA9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_6E3F197874DC5A4E527F816A7C611E1D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68" xlink:to="loc_us-gaap_AgencySecuritiesMember_6E3F197874DC5A4E527F816A7C611E1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_0DCF946E94B43726F0E0816A7C61D667" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_85D987E5BB3CFCD39BDD816A7C61AC68" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_0DCF946E94B43726F0E0816A7C61D667" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D10705449E42A0F9EBC5816A7C61BB74" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_C47DF07F8AD5990C230F816A7C610975" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D10705449E42A0F9EBC5816A7C61BB74" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D10705449E42A0F9EBC5816A7C61BB74" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D10705449E42A0F9EBC5816A7C61BB74" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityUpTo30DaysMember" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_FCBE6D04EE2A46B13FA9816A7C61854F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_FCBE6D04EE2A46B13FA9816A7C61854F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_Maturity31To59DaysMember" xlink:label="loc_agnc_Maturity31To59DaysMember_1F8D59E2CED795597B29816A7C61041E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:to="loc_agnc_Maturity31To59DaysMember_1F8D59E2CED795597B29816A7C61041E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_Maturity60To90DaysMember" xlink:label="loc_agnc_Maturity60To90DaysMember_9D699894E04694A09E01816A7C613BBC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:to="loc_agnc_Maturity60To90DaysMember_9D699894E04694A09E01816A7C613BBC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityOver90DaysMember" xlink:label="loc_us-gaap_MaturityOver90DaysMember_D686ECC5F7ECB300AF83816A7C611065" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:to="loc_us-gaap_MaturityOver90DaysMember_D686ECC5F7ECB300AF83816A7C611065" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityOvernightMember" xlink:label="loc_us-gaap_MaturityOvernightMember_375CBC75D60D0E4BBAF6816A7C613B8A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_9B1184622D0643585513816A7C611558" xlink:to="loc_us-gaap_MaturityOvernightMember_375CBC75D60D0E4BBAF6816A7C613B8A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RetainedInterestsinConsolidatedVIEsPledgedasCollateralUnderRepurchaseAgreements" xlink:label="loc_agnc_RetainedInterestsinConsolidatedVIEsPledgedasCollateralUnderRepurchaseAgreements_3EA27F7D816FF692B606816A7C615AD6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:to="loc_agnc_RetainedInterestsinConsolidatedVIEsPledgedasCollateralUnderRepurchaseAgreements_3EA27F7D816FF692B606816A7C615AD6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue" xlink:label="loc_us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue_25586A293E03998368EF816A7C612F1F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:to="loc_us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue_25586A293E03998368EF816A7C612F1F" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost" xlink:label="loc_agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost_8AFFA5E8F76E2ECE11F9816A7C61CD1E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:to="loc_agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost_8AFFA5E8F76E2ECE11F9816A7C61CD1E" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest" xlink:label="loc_agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest_3FE97E825C502F1D7559816A7C61B265" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_A91520A5641BF7A983D4816A7C61CA8F" xlink:to="loc_agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest_3FE97E825C502F1D7559816A7C61B265" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebt" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtFederalHomeLoanBankAdvancesAndWeightedAverageInterestRatesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtLineItems" xlink:label="loc_us-gaap_ShortTermDebtLineItems_65B823946D1D43D793BB6272BD78C430" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShortTermDebtTable" xlink:label="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_65B823946D1D43D793BB6272BD78C430" xlink:to="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_DFBCC7E7E8A2B9D481EA6272BD772C1E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:to="loc_us-gaap_RangeAxis_DFBCC7E7E8A2B9D481EA6272BD772C1E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_97786C0B8808730F03E46272BD772209_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_DFBCC7E7E8A2B9D481EA6272BD772C1E" xlink:to="loc_us-gaap_RangeMember_97786C0B8808730F03E46272BD772209_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_97786C0B8808730F03E46272BD772209" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_DFBCC7E7E8A2B9D481EA6272BD772C1E" xlink:to="loc_us-gaap_RangeMember_97786C0B8808730F03E46272BD772209" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_615934807C05930BD4116272BD77399E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_615934807C05930BD4116272BD77399E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_F0C79D5982EB2D0576F96272BD7757C3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_615934807C05930BD4116272BD77399E" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_F0C79D5982EB2D0576F96272BD7757C3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_F0C79D5982EB2D0576F96272BD7757C3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_615934807C05930BD4116272BD77399E" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_F0C79D5982EB2D0576F96272BD7757C3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A37to48monthsMember" xlink:label="loc_agnc_A37to48monthsMember_E31D798BAF8EB18EF9FD6272BD77AB30" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_F0C79D5982EB2D0576F96272BD7757C3" xlink:to="loc_agnc_A37to48monthsMember_E31D798BAF8EB18EF9FD6272BD77AB30" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FederalHomeLoanBankAdvancesMaturityPeriodAxis" xlink:label="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodAxis_E04765E6943A28AC5A5C6272BD786983" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:to="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodAxis_E04765E6943A28AC5A5C6272BD786983" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain" xlink:label="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodAxis_E04765E6943A28AC5A5C6272BD786983" xlink:to="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633_default" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain" xlink:label="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodAxis_E04765E6943A28AC5A5C6272BD786983" xlink:to="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A49to60MonthsMember" xlink:label="loc_agnc_A49to60MonthsMember_F9E8B6DEE2B329D829B66272BD7864EC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_agnc_A49to60MonthsMember_F9E8B6DEE2B329D829B66272BD7864EC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A37to48monthsMember" xlink:label="loc_agnc_A37to48monthsMember_628F5627B20F77D47F896272BD786C6C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_agnc_A37to48monthsMember_628F5627B20F77D47F896272BD786C6C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityUpTo30DaysMember" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_31CB99CD829C749DED676272BD78F0F1" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_31CB99CD829C749DED676272BD78F0F1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A10to12MonthsMember" xlink:label="loc_agnc_A10to12MonthsMember_511EC8C2B627F5F7F7D66272BD78A307" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_agnc_A10to12MonthsMember_511EC8C2B627F5F7F7D66272BD78A307" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ThirtyOneToNinetyMember" xlink:label="loc_agnc_ThirtyOneToNinetyMember_8431C0737341653BF4816272BD785D2D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_agnc_ThirtyOneToNinetyMember_8431C0737341653BF4816272BD785D2D" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A13MonthsMember" xlink:label="loc_agnc_A13MonthsMember_DA738B1251FDFF0279A16272BD78A706" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_FederalHomeLoanBankAdvancesMaturityPeriodDomain_4057682CB540698E82426272BD78D633" xlink:to="loc_agnc_A13MonthsMember_DA738B1251FDFF0279A16272BD78A706" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_6A5A6C8CCA5C0C0F64F96272BD78BF2F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_6A5A6C8CCA5C0C0F64F96272BD78BF2F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_EA41A5EDD050314898AE6272BD7827BF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_6A5A6C8CCA5C0C0F64F96272BD78BF2F" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_EA41A5EDD050314898AE6272BD7827BF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_EA41A5EDD050314898AE6272BD7827BF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_6A5A6C8CCA5C0C0F64F96272BD78BF2F" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_EA41A5EDD050314898AE6272BD7827BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_4C9E950C64BA2FA30F3A6272BD78EF7C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_2E6A94C697229C22FA866272BD773021" xlink:to="loc_us-gaap_DebtInstrumentAxis_4C9E950C64BA2FA30F3A6272BD78EF7C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_C4C6CE7DAEA1419688756272BD78DE95_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_4C9E950C64BA2FA30F3A6272BD78EF7C" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_C4C6CE7DAEA1419688756272BD78DE95_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_C4C6CE7DAEA1419688756272BD78DE95" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_4C9E950C64BA2FA30F3A6272BD78EF7C" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_C4C6CE7DAEA1419688756272BD78DE95" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtPercentageBearingFixedInterestRate" xlink:label="loc_us-gaap_ShortTermDebtPercentageBearingFixedInterestRate_BB13E70890307149BBE46272BD78AD54" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_65B823946D1D43D793BB6272BD78C430" xlink:to="loc_us-gaap_ShortTermDebtPercentageBearingFixedInterestRate_BB13E70890307149BBE46272BD78AD54" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_FHLBWeightedAverageDaystoMaturity" xlink:label="loc_agnc_FHLBWeightedAverageDaystoMaturity_7EF67E8BB91C687AC74A6272BD785CA9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_65B823946D1D43D793BB6272BD78C430" xlink:to="loc_agnc_FHLBWeightedAverageDaystoMaturity_7EF67E8BB91C687AC74A6272BD785CA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdvancesFromFederalHomeLoanBanks" xlink:label="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_8DB69AC6226997EA60846272BD788002" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_65B823946D1D43D793BB6272BD78C430" xlink:to="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_8DB69AC6226997EA60846272BD788002" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems_76A59633414612058AD67C66782A5133" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable" xlink:label="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems_76A59633414612058AD67C66782A5133" xlink:to="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentAxis" xlink:label="loc_invest_InvestmentAxis_6C785280697234AD72537C8F2B337847" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:to="loc_invest_InvestmentAxis_6C785280697234AD72537C8F2B337847" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_8DF05206D310C29D950B7C8F2B3AA37E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentAxis_6C785280697234AD72537C8F2B337847" xlink:to="loc_invest_InvestmentDomain_8DF05206D310C29D950B7C8F2B3AA37E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_8DF05206D310C29D950B7C8F2B3AA37E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentAxis_6C785280697234AD72537C8F2B337847" xlink:to="loc_invest_InvestmentDomain_8DF05206D310C29D950B7C8F2B3AA37E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_73C3EA6E9E96AF04D3A97C8F2C5D6F75" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentDomain_8DF05206D310C29D950B7C8F2B3AA37E" xlink:to="loc_us-gaap_AgencySecuritiesMember_73C3EA6E9E96AF04D3A97C8F2C5D6F75" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtSecurityAxis" xlink:label="loc_us-gaap_DebtSecurityAxis_9B3369F4D54EC54AC4357C6678293BC6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:to="loc_us-gaap_DebtSecurityAxis_9B3369F4D54EC54AC4357C6678293BC6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_25825985E891E7C8CB677C667829F34C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtSecurityAxis_9B3369F4D54EC54AC4357C6678293BC6" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_25825985E891E7C8CB677C667829F34C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_25825985E891E7C8CB677C667829F34C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtSecurityAxis_9B3369F4D54EC54AC4357C6678293BC6" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_25825985E891E7C8CB677C667829F34C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_2D8277CC38358349F76C7C667829A491" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_25825985E891E7C8CB677C667829F34C" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_2D8277CC38358349F76C7C667829A491" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_C809DD674AEB2992DB687C6678292B21" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_C809DD674AEB2992DB687C6678292B21" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_E5787AE5D673CA3EBBBE7C6678299330_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_C809DD674AEB2992DB687C6678292B21" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_E5787AE5D673CA3EBBBE7C6678299330_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_E5787AE5D673CA3EBBBE7C6678299330" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_C809DD674AEB2992DB687C6678292B21" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_E5787AE5D673CA3EBBBE7C6678299330" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityOvernightMember" xlink:label="loc_us-gaap_MaturityOvernightMember_FCD3224222C7F563D9EF7C66782AFECA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_E5787AE5D673CA3EBBBE7C6678299330" xlink:to="loc_us-gaap_MaturityOvernightMember_FCD3224222C7F563D9EF7C66782AFECA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_21ADF9300BE5D25A6E8B7C66782A8B47" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:to="loc_us-gaap_DerivativeByNatureAxis_21ADF9300BE5D25A6E8B7C66782A8B47" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_90851FE9916315EF73757C66782A78EF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_21ADF9300BE5D25A6E8B7C66782A8B47" xlink:to="loc_us-gaap_DerivativeNameDomain_90851FE9916315EF73757C66782A78EF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_90851FE9916315EF73757C66782A78EF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_21ADF9300BE5D25A6E8B7C66782A8B47" xlink:to="loc_us-gaap_DerivativeNameDomain_90851FE9916315EF73757C66782A78EF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember" xlink:label="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_E1193986D0BFD6AA45AD7C66782ADD0C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_90851FE9916315EF73757C66782A78EF" xlink:to="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_E1193986D0BFD6AA45AD7C66782ADD0C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_344290978F6D7F14251D7C66782AAE7F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_887523F02758B7FAC9017C6678293C39" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_344290978F6D7F14251D7C66782AAE7F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_85FF197C2838425184D07C66782A97DC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_344290978F6D7F14251D7C66782AAE7F" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_85FF197C2838425184D07C66782A97DC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_85FF197C2838425184D07C66782A97DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_344290978F6D7F14251D7C66782AAE7F" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_85FF197C2838425184D07C66782A97DC" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_4D84AC6D9ABCF4BFC16D7C66782A8A73" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_85FF197C2838425184D07C66782A97DC" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_4D84AC6D9ABCF4BFC16D7C66782A8A73" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_63811F7D417B4D901B877C66782A0607" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems_76A59633414612058AD67C66782A5133" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_63811F7D417B4D901B877C66782A0607" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DerivativeForwardSettlementValue" xlink:label="loc_agnc_DerivativeForwardSettlementValue_A58CE0B0AD8003CC83F77C66782AE6E8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems_76A59633414612058AD67C66782A5133" xlink:to="loc_agnc_DerivativeForwardSettlementValue_A58CE0B0AD8003CC83F77C66782AE6E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_382F869FFBC8B5FA4C637C66782AD8A0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseLineItems_76A59633414612058AD67C66782A5133" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_382F869FFBC8B5FA4C637C66782AD8A0" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_81B51D8A8F213CEEA65F816A7DAEE358" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable" xlink:label="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_81B51D8A8F213CEEA65F816A7DAEE358" xlink:to="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtSecurityAxis" xlink:label="loc_us-gaap_DebtSecurityAxis_6B2798DEDC0F02871326816A7DAE2185" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:to="loc_us-gaap_DebtSecurityAxis_6B2798DEDC0F02871326816A7DAE2185" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_3E1D242010C4E248FFB6816A7DAE4A3F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtSecurityAxis_6B2798DEDC0F02871326816A7DAE2185" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_3E1D242010C4E248FFB6816A7DAE4A3F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_3E1D242010C4E248FFB6816A7DAE4A3F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtSecurityAxis_6B2798DEDC0F02871326816A7DAE2185" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_3E1D242010C4E248FFB6816A7DAE4A3F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_A913DE23BA6778508331816A7DAE35C0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_3E1D242010C4E248FFB6816A7DAE4A3F" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_A913DE23BA6778508331816A7DAE35C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentAxis" xlink:label="loc_invest_InvestmentAxis_EE30B1D824EF387FC8E6816A7DAEBC69" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:to="loc_invest_InvestmentAxis_EE30B1D824EF387FC8E6816A7DAEBC69" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_30DBCEC27E21D1515831816A7DAEC15A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentAxis_EE30B1D824EF387FC8E6816A7DAEBC69" xlink:to="loc_invest_InvestmentDomain_30DBCEC27E21D1515831816A7DAEC15A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_30DBCEC27E21D1515831816A7DAEC15A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentAxis_EE30B1D824EF387FC8E6816A7DAEBC69" xlink:to="loc_invest_InvestmentDomain_30DBCEC27E21D1515831816A7DAEC15A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_68921B57AF1182B85051816A7DAE3C80" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentDomain_30DBCEC27E21D1515831816A7DAEC15A" xlink:to="loc_us-gaap_AgencySecuritiesMember_68921B57AF1182B85051816A7DAE3C80" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_CE2ED2AC96F8DA35B5C3816A7DAE8C36" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:to="loc_us-gaap_DebtInstrumentAxis_CE2ED2AC96F8DA35B5C3816A7DAE8C36" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_03D2C83B7DDBC27DEFCD816A7DAEB680_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_CE2ED2AC96F8DA35B5C3816A7DAE8C36" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_03D2C83B7DDBC27DEFCD816A7DAEB680_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_03D2C83B7DDBC27DEFCD816A7DAEB680" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_CE2ED2AC96F8DA35B5C3816A7DAE8C36" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_03D2C83B7DDBC27DEFCD816A7DAEB680" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_F936C2835E8FA655DEC6816A7DAE9546" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_03D2C83B7DDBC27DEFCD816A7DAEB680" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_F936C2835E8FA655DEC6816A7DAE9546" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D79E628A4642DE72985D816A7DAEE964" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_6F62F722991A7867A10B816A7DAE31D9" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D79E628A4642DE72985D816A7DAEE964" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D79E628A4642DE72985D816A7DAEE964" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_D79E628A4642DE72985D816A7DAEE964" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityUpTo30DaysMember" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_6C395B7C7F69EB613AE2816A7DAE5C39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_6C395B7C7F69EB613AE2816A7DAE5C39" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_ThirtyOneToNinetyMember" xlink:label="loc_agnc_ThirtyOneToNinetyMember_952AD0040C8FCB2B021E816A7DAE98BD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_ThirtyOneToNinetyMember_952AD0040C8FCB2B021E816A7DAE98BD" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A4to6MonthsMember" xlink:label="loc_agnc_A4to6MonthsMember_201B28D0C06A8C7D72F9816A7DAE14D3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A4to6MonthsMember_201B28D0C06A8C7D72F9816A7DAE14D3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A7to9monthsMember" xlink:label="loc_agnc_A7to9monthsMember_0EE992C4B74156A36D10816A7DAE4598" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A7to9monthsMember_0EE992C4B74156A36D10816A7DAE4598" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A10to12MonthsMember" xlink:label="loc_agnc_A10to12MonthsMember_6A208542ECC5E1CE94C7816A7DAE1F2B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A10to12MonthsMember_6A208542ECC5E1CE94C7816A7DAE1F2B" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A13to24MonthsMember" xlink:label="loc_agnc_A13to24MonthsMember_A5D9F3EF2B4DE82F4F89816A7DAE37DB" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A13to24MonthsMember_A5D9F3EF2B4DE82F4F89816A7DAE37DB" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A25to36monthsMember" xlink:label="loc_agnc_A25to36monthsMember_6B0184E3F65703D5E939816A7DAEE9EF" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A25to36monthsMember_6B0184E3F65703D5E939816A7DAEE9EF" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A37to48monthsMember" xlink:label="loc_agnc_A37to48monthsMember_5EB8DBED1BA493AFD1C5816A7DAEF342" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A37to48monthsMember_5EB8DBED1BA493AFD1C5816A7DAEF342" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_A49to60MonthsMember" xlink:label="loc_agnc_A49to60MonthsMember_70F076A7CCE85B4452EF816A7DAE3F09" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_agnc_A49to60MonthsMember_70F076A7CCE85B4452EF816A7DAE3F09" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaturityOvernightMember" xlink:label="loc_us-gaap_MaturityOvernightMember_00C9DA42ADFEDC829B74816A7DAE1B84" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_1D8E8180C9B68B1643F3816A7DAE3B06" xlink:to="loc_us-gaap_MaturityOvernightMember_00C9DA42ADFEDC829B74816A7DAE1B84" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_5DE76B77C73197C75A7D816A7DAEF292" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_81B51D8A8F213CEEA65F816A7DAEE358" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_5DE76B77C73197C75A7D816A7DAEF292" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_309E47E9C63F16287DED816A7DAE4A3A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_81B51D8A8F213CEEA65F816A7DAEE358" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_309E47E9C63F16287DED816A7DAE4A3A" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity" xlink:label="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_2ED743787979F8E75E00816A7DAED836" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_81B51D8A8F213CEEA65F816A7DAEE358" xlink:to="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_2ED743787979F8E75E00816A7DAED836" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquity" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7DDD9AD4A5591DC52CC05EB7A75F8781" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7DDD9AD4A5591DC52CC05EB7A75F8781" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_E73728EAC62F12F682E75EB7A75FEB39" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7DDD9AD4A5591DC52CC05EB7A75F8781" xlink:to="loc_us-gaap_DerivativeByNatureAxis_E73728EAC62F12F682E75EB7A75FEB39" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_6B0A56AB11FC359B85A45EB7A75F32E7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_E73728EAC62F12F682E75EB7A75FEB39" xlink:to="loc_us-gaap_DerivativeNameDomain_6B0A56AB11FC359B85A45EB7A75F32E7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_6B0A56AB11FC359B85A45EB7A75F32E7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_E73728EAC62F12F682E75EB7A75FEB39" xlink:to="loc_us-gaap_DerivativeNameDomain_6B0A56AB11FC359B85A45EB7A75F32E7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_99E0ADB5E6CB862FEE9A5EB7A75F8195" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_6B0A56AB11FC359B85A45EB7A75F32E7" xlink:to="loc_us-gaap_InterestRateSwapMember_99E0ADB5E6CB862FEE9A5EB7A75F8195" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8A6158B72E81597093695EB7A75F7AD9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7DDD9AD4A5591DC52CC05EB7A75F8781" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8A6158B72E81597093695EB7A75F7AD9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8E0D0D4972AEFBE331505EB7A75F9AE8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8A6158B72E81597093695EB7A75F7AD9" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8E0D0D4972AEFBE331505EB7A75F9AE8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8E0D0D4972AEFBE331505EB7A75F9AE8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8A6158B72E81597093695EB7A75F7AD9" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8E0D0D4972AEFBE331505EB7A75F9AE8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember" xlink:label="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_02F8338DA6CA71CAB3535EB7A75F1A52" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_8E0D0D4972AEFBE331505EB7A75F9AE8" xlink:to="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_02F8338DA6CA71CAB3535EB7A75F1A52" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_526435C1DF02AC6E8FF15EB7A760DC47" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7DDD9AD4A5591DC52CC05EB7A75F8781" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_526435C1DF02AC6E8FF15EB7A760DC47" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0F33C52837EC37CAC1AA5EB7A7609022_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_526435C1DF02AC6E8FF15EB7A760DC47" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0F33C52837EC37CAC1AA5EB7A7609022_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0F33C52837EC37CAC1AA5EB7A7609022" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_526435C1DF02AC6E8FF15EB7A760DC47" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0F33C52837EC37CAC1AA5EB7A7609022" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_0DD7E7F6B068A19EC5395EB7A7657A97" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0F33C52837EC37CAC1AA5EB7A7609022" xlink:to="loc_us-gaap_AgencySecuritiesMember_0DD7E7F6B068A19EC5395EB7A7657A97" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_58C805161A05CCAF73145EB7A765E176" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_58C805161A05CCAF73145EB7A765E176" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge" xlink:label="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_65CCBDCF21F23E6E94485EB7A765A83F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_65CCBDCF21F23E6E94485EB7A765A83F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_C4EC949542CE0BE9A88A5EB7A765F4CA" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_C4EC949542CE0BE9A88A5EB7A765F4CA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_4BFA2EAD4E848D31F0745EB7A76513D1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_4BFA2EAD4E848D31F0745EB7A76513D1" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization" xlink:label="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_601AEE65F51BDF2C6B145EB7A765626D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_601AEE65F51BDF2C6B145EB7A765626D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_265FADC4250EBBDC07A35EB7A765B2A3" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_265FADC4250EBBDC07A35EB7A765B2A3" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_TotalReclassOfOtherComprehensiveIncome" xlink:label="loc_agnc_TotalReclassOfOtherComprehensiveIncome_E420B12952D5E224AD045EB7A766455B" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8003BAAC875E00DB92D15EB7A765E581" xlink:to="loc_agnc_TotalReclassOfOtherComprehensiveIncome_E420B12952D5E224AD045EB7A766455B" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8F246D4B14DD1560B7ED62929995B6A5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8F246D4B14DD1560B7ED62929995B6A5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_32A9E523EF35A8CDEF04629299950E92" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8F246D4B14DD1560B7ED62929995B6A5" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_32A9E523EF35A8CDEF04629299950E92" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_6FF7FAF7AB8FEC6EC669629299969BF6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32A9E523EF35A8CDEF04629299950E92" xlink:to="loc_us-gaap_EquityComponentDomain_6FF7FAF7AB8FEC6EC669629299969BF6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_6FF7FAF7AB8FEC6EC669629299969BF6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32A9E523EF35A8CDEF04629299950E92" xlink:to="loc_us-gaap_EquityComponentDomain_6FF7FAF7AB8FEC6EC669629299969BF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_14A3A4B2EFE755CB625E629299969838" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FF7FAF7AB8FEC6EC669629299969BF6" xlink:to="loc_us-gaap_CommonStockMember_14A3A4B2EFE755CB625E629299969838" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_8B211FD6224BAEC9D00B6292999625C6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_8B211FD6224BAEC9D00B6292999625C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_E667131F0D59121190B6629299960743" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_E667131F0D59121190B6629299960743" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_05D00EAF2849BD361D9D6292999648CD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_05D00EAF2849BD361D9D6292999648CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_E8D0743032CA203D0583629299967BAD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_E8D0743032CA203D0583629299967BAD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_04EB2BFBB6341DB2C3BD62929996FB41" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6066812087F70274182F629299968F40" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_04EB2BFBB6341DB2C3BD62929996FB41" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityPreferredStockDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0DB77BF11327393CAC305EB7A797A18C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0DB77BF11327393CAC305EB7A797A18C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_379B3219C7FD6D3950795EB7A7979F37" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0DB77BF11327393CAC305EB7A797A18C" xlink:to="loc_us-gaap_StatementClassOfStockAxis_379B3219C7FD6D3950795EB7A7979F37" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_379B3219C7FD6D3950795EB7A7979F37" xlink:to="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_379B3219C7FD6D3950795EB7A7979F37" xlink:to="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredClassAMember" xlink:label="loc_us-gaap_PreferredClassAMember_91594B4E0A9E6948F04F5EB7A79755EA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:to="loc_us-gaap_PreferredClassAMember_91594B4E0A9E6948F04F5EB7A79755EA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_6215E4185E2DDE56CEC25EB7A7970DA1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_6215E4185E2DDE56CEC25EB7A7970DA1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredClassBMember" xlink:label="loc_us-gaap_PreferredClassBMember_57F4A971250ED008C2F15EB7A798391E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:to="loc_us-gaap_PreferredClassBMember_57F4A971250ED008C2F15EB7A798391E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_735583E384AF353DD96E5EB7A7987EDE" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_BCE33F8AE0D4688388BD5EB7A7978F4E" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_735583E384AF353DD96E5EB7A7987EDE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_0B79EEF4111A9FF79AE25EB7A79865B9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_0B79EEF4111A9FF79AE25EB7A79865B9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance_FA3E4B654366C21DF9A95EB7A79EEF57" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance_FA3E4B654366C21DF9A95EB7A79EEF57" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockDividendRatePercentage" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_7CEDF5FEDF3DFA4488845EB7A79E9DC8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_7CEDF5FEDF3DFA4488845EB7A79E9DC8" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PreferredStockAuthorizedButNotIssued" xlink:label="loc_agnc_PreferredStockAuthorizedButNotIssued_562CF2098B9045435F735EB7A79EB074" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_agnc_PreferredStockAuthorizedButNotIssued_562CF2098B9045435F735EB7A79EB074" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_587737BAC50B05FB073A5EB7A79EC636" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_587737BAC50B05FB073A5EB7A79EC636" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_6E58D3542854FCF3B58D5EB7A79EAFCD" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_6E58D3542854FCF3B58D5EB7A79EAFCD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockLiquidationPreference" xlink:label="loc_us-gaap_PreferredStockLiquidationPreference_B5E49CECFA43E64402165EB7A79EB1E6" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockLiquidationPreference_B5E49CECFA43E64402165EB7A79EB1E6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_079DC680466EFE2974E65EB7A79E29F6" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockSharesIssued_079DC680466EFE2974E65EB7A79E29F6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_87DCDF8BBA27EF5CA3275EB7A79E692C" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_SharePrice_87DCDF8BBA27EF5CA3275EB7A79E692C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_E693848C46D56F6EFBA25EB7A79E4031" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_us-gaap_PreferredStockValue_E693848C46D56F6EFBA25EB7A79E4031" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_PreferredStockPercentInterestPerShare" xlink:label="loc_agnc_PreferredStockPercentInterestPerShare_5571E334DFBC98C7589B5EB7A79E1D3C" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1514BFF1AC741C7880425EB7A79891E7" xlink:to="loc_agnc_PreferredStockPercentInterestPerShare_5571E334DFBC98C7589B5EB7A79E1D3C" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SubsequentEvent" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SubsequentEventDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_A6E705FA8057371502175EB7A6CC0695" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_FFBCB3F9434877196F065EB7A6CB6DA1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_A6E705FA8057371502175EB7A6CC0695" xlink:to="loc_us-gaap_SubsequentEventTable_FFBCB3F9434877196F065EB7A6CB6DA1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_5589C93E8525BA3C94CB5EB7A6CBC798" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_FFBCB3F9434877196F065EB7A6CB6DA1" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_5589C93E8525BA3C94CB5EB7A6CBC798" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_F071EB6399A2AC1A669F5EB7A6CB2FC0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5589C93E8525BA3C94CB5EB7A6CBC798" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_F071EB6399A2AC1A669F5EB7A6CB2FC0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_F071EB6399A2AC1A669F5EB7A6CB2FC0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5589C93E8525BA3C94CB5EB7A6CBC798" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_F071EB6399A2AC1A669F5EB7A6CB2FC0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_2E435317870F7811B84B5EB7A6CC03EE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_F071EB6399A2AC1A669F5EB7A6CB2FC0" xlink:to="loc_us-gaap_SubsequentEventMember_2E435317870F7811B84B5EB7A6CC03EE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_2E50C5DC85516A19F7925EB7A6CCC067" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_A6E705FA8057371502175EB7A6CC0695" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_2E50C5DC85516A19F7925EB7A6CCC067" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesAccountingPoliciesPolicies" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_BF29CD427822310B514F816A7E80ADF7" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_C89637669CAED9CE95C5816A7E807664" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_BF29CD427822310B514F816A7E80ADF7" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_C89637669CAED9CE95C5816A7E807664" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8CAAE1431E48A0790395816A7E80069F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_C89637669CAED9CE95C5816A7E807664" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8CAAE1431E48A0790395816A7E80069F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_45436BB485A168B6FCF6816A7E80A505_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8CAAE1431E48A0790395816A7E80069F" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_45436BB485A168B6FCF6816A7E80A505_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_45436BB485A168B6FCF6816A7E80A505" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_8CAAE1431E48A0790395816A7E80069F" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_45436BB485A168B6FCF6816A7E80A505" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember" xlink:label="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_357C8E6D60B54AAAF338816A7E801046" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_45436BB485A168B6FCF6816A7E80A505" xlink:to="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_357C8E6D60B54AAAF338816A7E801046" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativesPolicyTextBlock" xlink:label="loc_us-gaap_DerivativesPolicyTextBlock_E53E9507F887C922421D816A7E80E5DE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_BF29CD427822310B514F816A7E80ADF7" xlink:to="loc_us-gaap_DerivativesPolicyTextBlock_E53E9507F887C922421D816A7E80E5DE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentPolicyTextBlock" xlink:label="loc_us-gaap_InvestmentPolicyTextBlock_0E3433B76B85CF68DDC4816A7E800A66" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_BF29CD427822310B514F816A7E80ADF7" xlink:to="loc_us-gaap_InvestmentPolicyTextBlock_0E3433B76B85CF68DDC4816A7E800A66" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_InterestIncomePolicyTextBlock" xlink:label="loc_agnc_InterestIncomePolicyTextBlock_6F551A874B8774F7D294816A7E8A0E9B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_BF29CD427822310B514F816A7E80ADF7" xlink:to="loc_agnc_InterestIncomePolicyTextBlock_6F551A874B8774F7D294816A7E8A0E9B" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_F47FBE7F4E3C68BFA546816A7E767B9C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_732A2E11A237E4F523D9816A7E76D70D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_F47FBE7F4E3C68BFA546816A7E767B9C" xlink:to="loc_us-gaap_DerivativeTable_732A2E11A237E4F523D9816A7E76D70D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_1C531146395762B0C8BD816A7E769B0E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_732A2E11A237E4F523D9816A7E76D70D" xlink:to="loc_us-gaap_RangeAxis_1C531146395762B0C8BD816A7E769B0E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_987924FCD8D54CB8CE3E816A7E760582_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_1C531146395762B0C8BD816A7E769B0E" xlink:to="loc_us-gaap_RangeMember_987924FCD8D54CB8CE3E816A7E760582_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_987924FCD8D54CB8CE3E816A7E760582" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_1C531146395762B0C8BD816A7E769B0E" xlink:to="loc_us-gaap_RangeMember_987924FCD8D54CB8CE3E816A7E760582" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_19519E921E10EE514B5F816A7E761758" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_732A2E11A237E4F523D9816A7E76D70D" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_19519E921E10EE514B5F816A7E761758" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_617B0DF7FCB8C8766A2C816A7E764E6C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_19519E921E10EE514B5F816A7E761758" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_617B0DF7FCB8C8766A2C816A7E764E6C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_617B0DF7FCB8C8766A2C816A7E764E6C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_19519E921E10EE514B5F816A7E761758" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_617B0DF7FCB8C8766A2C816A7E764E6C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_095E00AF90E88483CBFE816A7E768ED4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_617B0DF7FCB8C8766A2C816A7E764E6C" xlink:to="loc_us-gaap_InterestRateSwapMember_095E00AF90E88483CBFE816A7E768ED4" xlink:type="arc" />
    <loc xlink:href="agnc-20160331.xsd#agnc_RequiredAnnualDistributionOfTaxableNetIncome" xlink:label="loc_agnc_RequiredAnnualDistributionOfTaxableNetIncome_BC5B70AEDC1CD45DECAB816A7E76CBC8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_F47FBE7F4E3C68BFA546816A7E767B9C" xlink:to="loc_agnc_RequiredAnnualDistributionOfTaxableNetIncome_BC5B70AEDC1CD45DECAB816A7E76CBC8" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesPolicy" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/UnauditedInterimConsolidatedFinancialStatements" xlink:type="extended" />
</linkbase>
