|FEDERAL NATIONAL MORTGAGE ASSOCIATION FANNIE MAE filed this Form 10-Q on 05/07/2015|
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS - (Continued)
We aggregate single-family HFI loans that are not individually impaired based on similar risk characteristics, for purposes of estimating incurred credit losses and establishing a collective single-family loss reserve using an econometric model that derives an overall loss reserve estimate. We base our allowance methodology on historical events and trends, such as loss severity (in event of default), default rates, and recoveries from mortgage insurance contracts and other credit enhancements. In addition, management performs a review of the observable data used in its estimate to ensure it is representative of prevailing economic conditions and other events existing as of the balance sheet date.
Individually impaired single-family loans currently include those restructured in a TDR and acquired credit-impaired loans. When a loan has been restructured, we measure impairment using a cash flow analysis discounted at the loan’s original effective interest rate. However, if we expect to recover our recorded investment in an individually impaired loan through probable foreclosure of the underlying collateral, we measure impairment based on the fair value of the collateral, reduced by estimated disposal costs and adjusted for estimated proceeds from mortgage, flood, or hazard insurance and other credit enhancements.
We identify multifamily loans for evaluation for impairment through a credit risk assessment process. If we determine that a multifamily loan is individually impaired, we generally measure impairment on that loan based on the fair value of the underlying collateral less estimated costs to sell the property. We establish a collective loss reserve for all loans in our multifamily guaranty book of business that are not individually impaired using an internal model that applies loss factors to loans in similar risk categories. Our loss factors are developed based on our historical default and loss severity experience.
The following table displays changes in single-family, multifamily and total allowance for loan losses for the three months ended March 31, 2015 and 2014.