As of December, the F.H.A. was insuring 5.8 million single-family residences that had a total loan balance of $750 billion. More than half a million of the loans were seriously delinquent and heading toward foreclosure.
Many of these troubled loans were made in 2007 and 2008 as the market was plunging. Last fall, the agency said its cash reserves had tumbled to 0.5 percent of its loans outstanding, far below the 2 percent mandated by Congress.