Fannie Mae scraps higher down-payment requirements

For example, mortgage insurers, whose backing is required for borrowers who can't afford the traditional 20 percent down payment on a home, have already flagged ZIP codes around the country where they refuse to insure some home loans.

In working with first-time homebuyers, she said, "we just keep sorting through guidelines until we find what works,"

Fannie Mae shares fell 34 cents to close at $28.89, while shares of Freddie Mac fell 30 cents to close at $26.97.