Item 3. Quantitative and Qualitative Disclosures about Market Risk
Market risk is the exposure to loss resulting from changes in market factors such as interest rates, foreign currency exchange rates, commodity prices and equity prices. The primary market risks that we are exposed to are interest rate, prepayment, spread, liquidity, extension and credit risk.
Interest Rate Risk
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 interest-earning assets and the interest expense incurred in connection with our interest-bearing liabilities, by affecting the spread between our interest-earning assets and interest-bearing liabilities. Changes in the level of interest rates can also affect the rate of prepayments of our securities and the value of the mortgage 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 utilize a variety of strategies to limit the effects of changes in interest rates on our operations. The principal instruments that we use are interest rate swaps, swaptions, U.S. Treasury securities and U.S. Treasury futures contracts. We also use forward contracts in the Agency RMBS TBA market to invest in and finance Agency securities as well as to periodically reduce our exposure to Agency RMBS. Derivative instruments may expose us 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 hedging purposes) may be adversely affected during any period as a result of changing interest rates including changes in the forward yield curve.
Primary measures of an instrument's price sensitivity to interest rate fluctuations are its duration and convexity. Duration measures the estimated percentage change in market value of our mortgage assets or our hedge portfolio that would be caused by a parallel change in short and long-term interest rates. The duration of our investment portfolio changes with interest rates and tends to increase when interest rates rise and decrease when interest rates fall. This "negative convexity" generally increases the interest rate exposure of our investment portfolio in excess of what is measured by duration alone.
We estimate the duration and convexity of our portfolio using both a third-party risk management system and market data. We review the duration estimates from the third-party model and may make adjustments based on our judgment. These adjustments are intended to better reflect the unique characteristics and market trading conventions associated with certain types of securities.
The table below quantifies the estimated changes in (i) net interest income (including periodic interest costs on our interest rate swaps); (ii) the fair value of our investment portfolio (including derivatives and other securities used for hedging purposes); and (iii) our tangible net asset value as of September 30, 2017 and December 31, 2016 should interest rates go up or down by 50 and 100 basis points, assuming instantaneous parallel shifts in the yield curve and including the impact of both duration and convexity.
All changes in income and value in the table below are measured as percentage changes from the base interest rate scenario. The base interest rate scenario assumes interest rates and prepayment projections as of September 30, 2017 and December 31, 2016. We apply a floor of 0% for the down rate scenarios on our interest bearing liabilities and the variable leg of our interest rate swaps, such that any hypothetical interest rate decrease would have a limited positive impact on our funding costs beyond a certain level.
Actual results could differ materially from estimates, especially in the current market environment. 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. Moreover, if different models were employed in the analysis, materially different projections could result. Lastly, while the table below reflects the estimated impact of interest rate changes on a static portfolio, we actively manage our portfolio and we continuously make adjustments to the size and composition of our asset and hedge portfolio.