Coruscation

In addition to shielding taxpayers from having to backstop an ever-expanding financial safety net for errant bankers, we also need protection from ballooning losses at Fannie and Freddie. This will require the F.H.F.A. to take other crucial steps.

Janet Tavakoli, president of Tavakoli Structured Finance, a consulting firm in Chicago, has provided a to-do list for officials at F.H.F.A.

In a presentation to the agency's supervision summit meeting last Wednesday in Washington, Ms. Tavakoli said that if the agency hoped to determine the credit risk lurking inside Fannie and Freddie, it needed to ascertain two things: the probability of default on those loans and the loss rates when probable defaults actually occur.

"They have to do their own statistical sampling of their portfolios to get a realistic idea of what those numbers are," Ms. Tavakoli said in an interview. "And it has to be rigorous because we don't know what kinds of impairments to expect from risky new mortgage products combined with a damaged economy and housing market."

The F.H.F.A. cannot rely on estimates from the credit ratings agencies about the extent of those losses, Ms. Tavakoli said. "The whole idea of relying on third parties has not worked," she said. "Once you feel better about the quality of your information, you'll feel more confident about making your next decision."