Mortgage Finance

This article by John Krainer of the San Francisco Fed has lots of information about the evolution of mortgage finance. This is important for thinking about the financial crisis of course. This is especially relevant for thinking about the relative importance of Government Sponsored Enterprises (GSE's) like Fannie Mae and Freddie Mac versus the non-agency securitizers. We can see, for example, that as the housing bubble proceeded the share of mortgages supplied by the GSE's declined:


We can also see that the non-agency lenders were more highly represented in the more risky types of mortgages at the height of the boom. For 2006 we have this picture:


Thus:

Compared with mortgages purchased by the GSEs, non-agency securitizations were much more likely to involve adjustable-rate mortgages, including option ARMs, to be rated as subprime, and to have less-than-full documentation of borrower income and assets. The median FICO credit score for the non-agency securitizations was about 30 points lower than for the mortgages held or guaranteed by Fannie Mae or Freddie Mac and much closer to the credit scores typically associated with loans guaranteed by Ginnie Mae.

These pictures are not consistent with the view that the housing bubble was the fault of the GSE's alone. Deteriorating standards seemed to accelerate as the GSE share fell.