The Federal Deposit Insurance Corp. has sold $490.7 million in troubled mortgage loans from 19 banks that failed between August 2008 and March 2009 as it works through an inventory of assets from the institutions it has taken over.

The FDIC said Thursday that the winning bidder in its auction, Charlotte, N.C.-based Roundpoint Mortgage Servicing Corp., paid $34.4 million for a 50 percent stake in a new company set up to hold the home mortgage loans. The FDIC has the other 50 percent.

About half the loans are 30 or more days delinquent, the FDIC said. The agency said about 80 percent of the homes involved are located in Arizona, Florida and Georgia, which are among the states with the highest numbers of failed banks.

Last year, 140 U.S. banks succumbed to the soured economy and a cascade of loan defaults — the most in a year since 1992 at the height of the savings-and-loan crisis. The failures compare with 25 in 2008 and three in 2007. They cost the federal deposit insurance fund, which fell into the red, more than $30 billion last year.

FDIC Chairman Sheila Bair has said bank failures are expected to be higher this year than in 2009, mainly driven by losses in commercial real estate loans.