Banks lend money (a mortgage) against your house. The banks then put 1,000 mortgages or so together and sell the package of mortgages to an investor in a “pooled mortgage”. Some pooled mortgages have held a government guarantee of performance through FHA (Federal Housing Administration), Fannie Mae, or Freddie Mac, other pools were not insured because they were supposedly riskier loans, as the borrowers did not qualify under loan risk guidelines established for Fannie Mae or Freddie Mac.

Under the new rules contained in Dodd-Frank, the original lender must retain 5% of the risk in the pool if it is not a federally guaranteed (e.g. FHA, Fannie Mae or Freddie Mac) loan pool.

CNBC.com editor John Carney writes that exempting FHA, Fannie Mae and Freddie Mac from the 5.0% risk retention requirement will destroy the private mortgage industry and make the US government the unintentional backer of all mortgages:

“…a little-noticed provision of the Dodd-Frank act threatens to undermine efforts at rebuilding an innovative and healthy private sector for mortgages. Under Dodd-Frank, financial firms that securitize mortgages are required to retain 5.0% of the risk of those securities. The goal, a laudable one, is to encourage companies to more closely monitor the quality of the mortgages they securitize (sell off in pooled bundles). But it is also likely to increase the cost of affected mortgages, because banks will seek to pass on the costs of the risk to home buyers. Mortgages guaranteed by the F.H.A., however, are exempt from the 5 percent risk-retention requirement. This means that lenders will find that it costs far more, and involves more risk, to offer mortgages they back themselves than those covered with a guarantee from the agency. There’s little doubt this will lead to a huge increase int he volume of business done by the F.H.A., as banks creating securities will seek out mortgages on which they don’t have to cover the risk. Purely private mortgages will quickly be pushed out of the market.”

The complete article by Mr. Carney was published in the NY Times on August 12, 2010.