NEW YORK - December 10, 2010 - Homes in the United States were expected to lose more than $1.7 trillion in value during 2010, exceeding their $1.05 trillion loss in 2009, as foreclosures accelerated, real estate data firm Zillow said on Thursday.

Zillow estimated, based on the first 11 months of 2010, less than a quarter of the 129 markets it tracks will show gains in total home values in 2010.

Among the 31 rising markets are Virginia Beach, Virginia, which is poised to gain $19.04 billion in total market value, Boston, up $10.77 billion and San Diego, up $10.18 billion.

Since the U.S. housing market peaked in 2006, Zillow estimates total housing value losses will top $9 trillion through the end of 2009.

That's more than 60% of U.S. annual economic output, estimated at around $14.8 trillion this year. It is more than eight times the cumulative $1.121 trillion appropriated cost of the wars in Iraq and Afghanistan through September 2010, according to a study by the Congressional Research Service.

Much of the lost value, more than $1 trillion, came in the second half of the year - after the expiration of tax credits for first-time homebuyers. The gains experienced by most markets came during the first half of the year.

"Thanks to high rates of foreclosure and negative equity, it does not appear that the first half of 2011 will bring much relief," Zillow public relations manager Katie Curnutte wrote in a blog post on the company's web site.

"However, the hope is that the market will reach a bottom sometime next year, and that average rates of appreciation will return sometime in the next three to five years," she added, likening house value declines for those planning to stay in their homes to unrealized stock market losses.