On April 25, the Federal Housing Finance Agency (FHFA) issued advisory bulletin AB 2018-02 to provide guidance for Federal Home Loan Banks (FHL Banks) on the use of models and methodologies when assessing mortgage asset credit risk. The advisory bulletin applies to FHL Banks that acquire Acquired Member Asset loans, mortgage-backed securities (MBS), and collateralized mortgage obligations. Exclusions from application of the guidance include certain mortgage-related assets that are guaranteed by, or operating with the capital support of, the U.S. government, including Fannie Mae and Freddie Mac. When selecting a credit risk model that is “sufficiently robust to produce meaningful loss estimates,” FHFA advises FHL Banks to consider the following when complying with regulatory requirements: (i) mortgage asset credit risk model selection; (ii) macroeconomic stress scenarios; (iii) stress scenario determinations; and (iv) credit enhancements. The guidance permits the exclusion of legacy private label MBS from application of the guidance where the stress loss estimates would be de minimis, and provides methods for determining estimated credit losses associated with securities that cannot be modeled.

The new guidance supplements general FHFA guidance on model risk management and takes effect January 1, 2019.