Interest rate risk is highly sensitive to many factors, including governmental monetary and tax policies, domestic and international economic and political considerations and other factors beyond our control.
Changes in the general level of interest rates can affect our net interest income, which is the difference between the interest income earned on interestearning assets and the interest expense incurred in connection with our interestbearing liabilities, by affecting the spread between our interestearning assets and interest bearing liabilities. Changes in the general level of interest rates can also affect our periodic settlements of interest rate swaps and the value of our interest rate swaps which impact our net income. Changes in the level of interest rates can also affect the rate of prepayments of our securities and the value of the agency securities that constitute our investment portfolio, which affects our net income and ability to realize gains from the sale of these assets and impacts our ability and the amount that we can borrow against these securities.
We may utilize a variety of financial instruments in order to limit the effects of changes in interest rates on our operations, including interest rate swap agreements, interest rate swaptions, interest rate cap or floor contracts and futures or forward contracts. We may also purchase or short TBA securities, U.S. Treasury securities and U.S. Treasury futures contracts, purchase or write put or call options on TBA securities or we may invest in other types of mortgage derivative securities, such as interestonly securities, and synthetic total return swaps, such as the Markit IOS Index. When we use these types of derivatives to hedge the risk of interestearning assets or interestbearing liabilities, we may be subject to certain risks, including the risk that losses on a hedge position will reduce the funds available for payments to holders of our common stock and that the losses may exceed the amount we invested in the instruments.
Our profitability and the value of our investment portfolio (including derivatives used for economic hedging purposes) may be adversely affected during any period as a result of changing interest rates including changes in the forward yield curve. The following table quantifies the estimated changes in net interest income (including periodic interest costs on our interest rate swaps) and the fair value of our investment portfolio value (including derivatives used for economic hedging purposes) should interest rates go up or down by 50 and 100 basis points, assuming the yield curves of the rate shocks will be parallel to each other and the current yield curve. These estimates were compiled using a combination of thirdparty services, market data and internal models. All changes in income and value are measured as percentage changes from the projected net interest income and investment portfolio value at the base interest rate scenario. The base interest rate scenario assumes interest rates as of December 31, 2011. Given the low level of interest rates, we also apply a floor of 0% for all anticipated interest rates included in our assumptions, such that any hypothetical interest rate decrease would have a limited positive impact on our funding costs beyond a certain level. However, because estimated prepayment speeds are impacted to a lessor degree by this floor, it is expected that an increase in our prepayment speeds as a result of a hypothetical interest rate decrease would result in an acceleration of our premium amortization and could result in reinvestment of such prepaid principal into lower yielding assets.
Actual results could differ materially from estimates, especially in the current market environment. The accuracy of the projected agency securities prices relies on assumptions that define specific agency securities spreads and varying prepayment assumptions at projected interest rate levels. To the extent that these estimates or other assumptions do not hold true, which is likely in a period of high price volatility, actual results will likely differ materially from projections and could be larger or smaller than the estimates in the table below. Moreover, if different models were employed in the analysis, materially different projections could result. In addition, the table below also does not include the impact of leverage, which generally has the effect of increasing the impact of the percentage change in projected portfolio value on stockholders' equity by a factor of leverage plus one. Lastly, while the tables below reflect the estimated impact of interest rate increases and decreases on a static portfolio, we may from time to time sell any of our agency securities as a part of our overall management of our investment portfolio.

   
Change in Interest Rate  Percentage Change in Projected Net Interest Income (1)   Percentage Change in Projected Portfolio Value, with Effect of Derivatives 
+100 Basis Points  3.1%   0.9% 
+50 Basis Points  0.4%   0.2% 
50 Basis Points  2.0%   0.2% 
100 Basis Points  13.2%   0.8% 
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(1) Includes the effect of periodic interest costs on our interest rate swaps.
Prepayment Risk
Premiums and discounts associated with the purchase of agency MBS are amortized or accreted into interest income over the projected lives of the securities, including contractual payments and estimated prepayments using the interest method. Changes