|FEDERAL NATIONAL MORTGAGE ASSOCIATION FANNIE MAE filed this Form 10-Q on 05/07/2015|
Interest Rate Sensitivity to Changes in Interest Rate Level and Slope of Yield Curve
Pursuant to a disclosure commitment with FHFA, we disclose on a monthly basis the estimated adverse impact on the fair value of our net portfolio that would result from the following hypothetical situations:
In measuring the estimated impact of changes in the level of interest rates, we assume a parallel shift in all maturities of the U.S. LIBOR interest rate swap curve.
In measuring the estimated impact of changes in the slope of the yield curve, we assume a constant 7-year rate and a shift of 16.7 basis points for the 1-year rate and 8.3 basis points for the 30-year rate. We believe the aforementioned interest rate shocks for our monthly disclosures represent moderate movements in interest rates over a one-month period.
Duration gap measures the price sensitivity of our assets and liabilities in our net portfolio to changes in interest rates by quantifying the difference between the estimated durations of our assets and liabilities. Our duration gap analysis reflects the extent to which the estimated maturity and repricing cash flows for our assets are matched, on average, over time and across interest rate scenarios to those of our liabilities. A positive duration gap indicates that the duration of our assets exceeds the duration of our liabilities. We disclose duration gap on a monthly basis under the caption “Interest Rate Risk Disclosures” in our Monthly Summary, which is available on our Web site and announced in a press release.
While our goal is to reduce the price sensitivity of our net portfolio to movements in interest rates, various factors can contribute to a duration gap that is either positive or negative. For example, changes in the market environment can increase or decrease the price sensitivity of our mortgage assets relative to the price sensitivity of our liabilities because of prepayment uncertainty associated with our assets. In a declining interest rate environment, prepayment rates tend to accelerate, thereby shortening the duration and average life of the fixed rate mortgage assets we hold in our net portfolio. Conversely, when interest rates increase, prepayment rates generally slow, which extends the duration and average life of our mortgage assets. Our debt and derivative instrument positions are used to manage the interest rate sensitivity of our retained mortgage portfolio and our investments in non-mortgage securities. As a result, the degree to which the interest rate sensitivity of our retained mortgage portfolio and our investments in non-mortgage securities is offset will be dependent upon, among other factors, the mix of funding and other risk management derivative instruments we use at any given point in time.
The market value sensitivities of our net portfolio are a function of both the duration and the convexity of our net portfolio. Duration provides a measure of the price sensitivity of a financial instrument to changes in interest rates while convexity reflects the degree to which the duration of the assets and liabilities in our net portfolio changes in response to a given change in interest rates. We use convexity measures to provide us with information about how quickly and by how much our net portfolio’s duration may change in different interest rate environments. The market value sensitivity of our net portfolio will depend on a number of factors, including the interest rate environment, modeling assumptions and the composition of assets and liabilities in our net portfolio, which vary over time.
Results of Interest Rate Sensitivity Measures
The interest rate risk measures discussed below exclude the impact of changes in the fair value of our guaranty assets and liabilities resulting from changes in interest rates. We exclude our guaranty business from these sensitivity measures based on our current assumption that the guaranty fee income generated from future business activity will largely replace guaranty fee income lost due to mortgage prepayments.
Table 36 displays the pre-tax market value sensitivity of our net portfolio to changes in the level of interest rates and the slope of the yield curve as measured on the last day of each period presented. In addition, Table 36 also provides the daily average, minimum, maximum and standard deviation values for duration gap and for the most adverse market value impact on the net portfolio to changes in the level of interest rates and the slope of the yield curve for the three months ended March 31, 2015 and 2014.
The sensitivity measures displayed in Table 36, which we disclose on a quarterly basis pursuant to a disclosure commitment with FHFA, are an extension of our monthly sensitivity measures. There are three primary differences between our monthly sensitivity disclosure and the quarterly sensitivity disclosure presented below: (1) the quarterly disclosure is expanded to include the sensitivity results for larger rate level shocks of plus or minus 100 basis points; (2) the monthly disclosure reflects the estimated pre-tax impact on the market value of our net portfolio calculated based on a daily average, while the quarterly disclosure reflects the estimated pre-tax impact calculated based on the estimated financial position of our net portfolio and