Nov. 9 (Bloomberg) -- The number of U.S. homeowners who owe more than their properties are worth fell in the third quarter as values stabilized and some homes were lost to foreclosure, Zillow.com said.

About 21 percent of owners of mortgaged homes were underwater, down from 23 percent in the second quarter, the Seattle-based real estate data provider said today in a report.

“The decline in the percentage of homeowners with negative equity is a positive sign, and is directly attributable to the stabilization of home values from the second quarter to the third,” Zillow Chief Economist Stan Humphries said in a statement. “It is also attributable to many homeowners who were previously underwater on their mortgage losing their homes to foreclosure.”

U.S. foreclosure filings climbed to 937,840 in the third quarter, a 23 percent increase from a year earlier, Irvine, California-based RealtyTrac Inc said Oct. 15. Zillow estimated that the median value of single-family houses, condominiums and cooperative apartments declined 6.9 percent in the same period.

The rate of decline slowed, as home values dropped 0.4 percent from the second quarter to a median of $190,400, Zillow said.

Bank sales of foreclosed properties accounted for 21 percent of all U.S. home sales in September, Zillow said. Such transactions made up 74 percent of sales in Merced, California; 69 percent in Stockton, California; and 68 percent in the Las Vegas area.

About 27 percent of homes sold nationwide went for less than the sellers originally paid for them, Zillow said.

Credit, Unemployment

Rising foreclosures that began with defaults on subprime mortgages, a global recession and increasing unemployment have hurt the U.S. housing market. Unemployment surged to a 26-year high of 10.2 percent in October, the Labor Department said last week. Payrolls fell by 190,000 workers.

Housing will hit bottom by March 2010, with lower-priced properties recovering value more quickly than expensive homes, First American CoreLogic said last month.

U.S. home values have dropped 21 percent from their peak, Zillow said.

The closely held company uses data from public records going back to 1996. Its mortgage figures come from information filed with individual counties.

To contact the reporter on this story: Daniel Taub in Los Angeles at dtaub@bloomberg.net.

Last Updated: November 9, 2009 00:01 EST