TAMPA - Tampa Bay home values continue to fall, owners owe more on mortgages than their homes are worth and many are selling for a loss, according to the real estate website Zillow.com.

Tampa area home values fell about 13 percent to a median value of $123,600 in the fourth quarter of 2009, according to a report released today. Values fell 0.8 percent from November to December. Zillow considers the Tampa area to be homes in Hernando, Hillsborough, Pasco and Pinellas counties.

Meanwhile, 46 percent of all owners of single-family homes with mortgages were underwater at the end of the fourth quarter. That's a little better than in the third quarter, when nearly 48 percent owed more than their home's value.

The area's hefty foreclosure rate and rising unemployment has pushed more owners into selling, even if they're upside down on their mortgages. Nearly 43 percent of all homes sold in the area in December were sold at a loss, Zillow said.

Nationally, home values continued to decline in the fourth quarter, leaving 21 percent of owners with negative equity, according to the Zillow report. U.S. home values fell 5 percent year-over-year and fell 0.5 percent in the fourth quarter when compared to the third quarter.

Twenty-nine of the 143 markets tracked by Zillow showed values flattened or decreased – after at least five consecutive monthly increases in 2009. This, according to Zillow, may mean prices will start consistently falling again in those areas.

"While we have seen strong stabilization in home values during 2009, there are clear signs that they will turn more negative in the near-term," said Zillow Chief Economist Stan Humphries. "What we saw in mid-2009 was a brief respite from a larger market correction that has not yet run its course."

Back in Tampa Bay, the report showed that not all neighborhoods are feeling the downturn equally.

For example, Tierra Verde saw values increase 0.42 percent in the fourth quarter, compared to the third quarter. In Redington Beach, on the other hand, values fell 4.6 percent in the fourth quarter.

Reporter Shannon Behnken can be reached at (813) 259-7804.