|FEDERAL NATIONAL MORTGAGE ASSOCIATION FANNIE MAE filed this Form 10-Q on 08/03/2017|
impact of changes in the spread between our mortgage assets and our debt and derivatives we use to hedge our position. Liquidity risk is the risk that we will not be able to meet our funding obligations in a timely manner. We describe our sources of interest rate risk exposure, business risks posed by changes in interest rates, and our strategy for managing interest rate risk and spread risk in “MD&A—Risk Management—Market Risk Management, Including Interest Rate Risk Management” and in “Risk Factors” in our 2016 Form 10-K.
Measurement of Interest Rate Risk
Below we present two quantitative metrics that provide estimates of our interest rate risk exposure: (1) fair value sensitivity of our net portfolio to changes in interest rate levels and slope of yield curve; and (2) duration gap. Our net portfolio consists of our retained mortgage portfolio assets; cash and other investments portfolio assets; our outstanding debt of Fannie Mae that is used to fund our retained mortgage portfolio assets and cash and other investments portfolio assets; mortgage commitments; and risk management derivatives. Risk management derivatives along with our debt instruments are used to manage interest rate risk.
The metrics presented are calculated using internal models that require standard assumptions regarding interest rates and future prepayments of principal over the remaining life of our securities. These assumptions are derived based on the characteristics of the underlying structure of the securities and historical prepayment rates experienced at specified interest rate levels, taking into account current market conditions, the current mortgage rates of our existing outstanding loans, loan age and other factors. On a continuous basis, management makes judgments about the appropriateness of the risk assessments and will make adjustments as necessary to properly assess our interest rate exposure and manage our interest rate risk. The methodologies used to calculate risk estimates are periodically changed on a prospective basis to reflect improvements in the underlying estimation process.
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 these interest rate shocks 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 website 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 depend on, among other factors, the mix of funding and other risk management derivative instruments we use at any given point in time.