American homeowners will collectively lose more than $2 trillion in home value by the end of 2008, according to a report released Monday. The real estate Web site Zillow.com calculated that home values have dropped 8.4% year-over-year during the first three quarters of 2008, compared with the same period of 2007. Some 11.7 million Americans are now "underwater," owing more on their mortgage balances than their homes are worth. "This year marked the acceleration of the market correction, and is likely to end with the eighth consecutive quarter of declines in home values," said Stan Humphries, Zillow's vice president of data and analytics. "Homeowners in most areas we cover are struggling with foreclosures pouring into the market, large amounts of negative equity and dropping home values." No bottom in sight One piece of good news is that in some, although not all, of the markets hardest hit by the downturn, such as San Francisco, San Diego and Punta Gorda, Fla., home values are not falling as steeply as they were. Offsetting that cause for optimism, however, are growing economic problems, especially increased job losses. The foreclosure picture is not likely to clear up in the coming months, according to Humphries. He expects to see more foreclosed, vacant homes added to already bulging inventories, sending prices spiraling down and putting more mortgage borrowers deeper underwater. Most of the subprime loans that will fail have already done so, but there are other toxic mortgage products whose default rates probably have not yet peaked. The number of option ARMs that fail, for instance, will continue to increase over the next few years according to Humphries. These loans allow homeowners to make minimum payments, which cause the loan principle to balloon. There are also lots of "liar loans" loans, which were issued without checking a borrower's assets or income, that are still going bad. Zillow's home value statistics closely track the foreclosure...