Our derivative agreements typically require that we pledge/receive collateral on such agreements to/from our counterparties in a similar manner as we are required to under our repurchase agreements. Our counterparties, or the central clearing agency, typically have the sole discretion to determine the value of the derivative instruments and the value of the collateral securing such instruments. In the event of a margin call, we must generally provide additional collateral on the same business day.
Similar to repurchase agreements, our use of derivatives exposes us to counterparty credit risk relating to potential losses that could be recognized in the event that our counterparties to these instruments fail to perform their obligations under the contracts. We minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings and by monitoring positions with individual counterparties. Excluding centrally cleared interest rate swaps, as of December 31, 2016, our amount at risk with any counterparty related to our interest rate swap and swaption agreements was less than 1% of our stockholders' equity. In the case of centrally cleared interest rate swap contracts, we could be exposed to credit risk if the central clearing agency or a clearing member defaults on its respective obligation to perform under the contract. However, we believe that the risk is minimal due to the exchange's initial and daily mark to market margin requirements and a clearinghouse guarantee fund and other resources that are available in the event of a clearing member default.
TBA Dollar Roll Transactions
TBA dollar roll transactions represent a form of off-balance sheet financing accounted for as derivative instruments and we may use them as a means of leveraging (or deleveraging) our investment portfolio through the use of long (or short) TBA contracts (see Notes 2 and 5 to our Consolidated Financial Statements in this Form 10-K).
Under certain market conditions, it may be uneconomical for us to roll our TBA contracts into future months and we may need to take or make physical delivery of the underlying securities. If we were required to take physical delivery to settle a long TBA contract, we would have to fund our total purchase commitment with cash or other financing sources and our liquidity position could be negatively impacted. As of December 31, 2016, we had a net long TBA position with a total market value and a total cost basis of $11.2 billion and $11.3 billion, respectively, and a net carrying value of $(147) million recognized in derivative assets/(liabilities), at fair value, on our Consolidated Balance Sheets in this Form 10-K.
Our TBA dollar roll contracts are also subject to margin requirements governed by the Mortgage-Backed Securities Division ("MBSD") of the FICC and by our prime brokerage agreements, which may establish margin levels in excess of the MBSD. Such provisions require that we establish an initial margin based on the notional value of the TBA contract, which is subject to increase if the estimated fair value of our TBA contract or the estimated fair value of our pledged collateral declines. The MBSD has the sole discretion to determine the value of our TBA contracts and of the pledged collateral securing such contracts. In the event of a margin call, we must generally provide additional collateral on the same business day.
Settlement of our TBA obligations by taking delivery of the underlying securities as well as satisfying margin requirements could negatively impact our liquidity position. However, since we do not use TBA dollar roll transactions as our primary source of financing, we believe that we will have adequate sources of liquidity to meet such obligations.
Federal Home Loan Bank Membership
In April 2015, our wholly-owned captive insurance subsidiary, Old Georgetown Insurance Co., LLC ("OGI"), was approved as a member of the FHLB of Des Moines. The FHLBs provide a variety of products and services to their members, including short and long-term secured loans, called "advances." In January 2016, the FHFA released its final rule on changes to regulations concerning FHLB membership criteria. The final rule terminated OGI's FHLB membership and required repayment of all advances at the earlier of their contractual maturity dates or a one year period after the effective date of the final rule that concluded in February 2017. As of December 31, 2016, we had $3.0 billion of FHLB advances outstanding with a weighted average interest rate of 0.73% and a weighted average remaining days to maturity of 28 days up to February 2017. We do not expect the termination of our FHLB membership to negatively impact our liquidity position, since FHLB advances do not represent our primary source of funding.
Asset Sales and TBA Eligible Securities
We maintain a portfolio of highly liquid mortgage-backed securities. We may sell our Agency securities through the TBA market by delivering them into TBA contracts, subject to "good delivery" provisions promulgated by SIFMA. We may alternatively sell Agency securities that have more unique attributes on a specified basis when such securities trade at a premium over generic TBA securities or if the securities are not otherwise eligible for TBA delivery. Since the TBA market is the second most liquid market (second to the U.S. Treasury market), maintaining a significant level of Agency securities eligible for TBA delivery enhances our liquidity profile and provides price support for our TBA eligible securities at or above generic TBA prices. As of December 31, 2016, approximately 86% of our fixed rate Agency RMBS portfolio was eligible for TBA delivery.