20% of Homes Underwater

Real estate website Zillow.com says 1 of every 5 U.S. home owners owed more on their mortgage than their home was worth in the 4th quarter. 

The percentage of American single-family homes with mortgages in negative equity rose to 21.4% in the 4th quarter from 21% in the 3rd quarter, according to the Zillow Real Estate Market Reports. 

U.S. home values declined again in the 4th quarter, as the Zillow Home Value Index fell -5% year-over-year and down -0.5% quarter-over-quarter, to $186,200. It was the 12th consecutive quarter of year-over-year declines, the reports showed.

"The prevalence of markets in or near a double-dip situation shows that we are not yet at the bottom, in terms of home values," Stan Humphries, Zillow chief economist, said in an interview.

One in 5, or 29 of the 143 markets tracked by Zillow, had at least 5 consecutive month-over-month increases in home values during 2009 before values began to flatten or fall again in the 2nd part of the year. These markets included the Boston, Atlanta and San Diego metropolitan areas.

Zillow said it defines a "double dip" as 2 periods of sustained declines in home values separated by a brief period of stabilization or recovery.

Foreclosure resales remained high, making up 20.3% of all U.S. home sales in December.

Foreclosure resales also made up the majority of sales in several metropolitan areas, including Merced, California, at 68.3%; Las Vegas, at 64%, and Modesto, California, at 62%.

Additionally, 28.5% of home sales nationwide sold for less than what the seller originally paid.  Home values increased year-over-year in 27 of 143 markets and remained flat in 15.