U.S. home prices have already stabilized in about a quarter of all housing markets, although further steep declines are still ahead for some of the areas hardest hit by the housing crisis, according to a new analysis by information technology firm Fiserv.

Although predicting that overall home prices will decline an average of 5.5 percent nationally over the next 12 months, the study concludes that prices in areas such as San Francisco, San Diego and Washington, DC have already stabilized. It forecasts that three-quarters of all U.S. housing markets will have stabilized by the end of the year.

Even so, it predicts significant price declines well into next year for areas like Phoenix, Miami and Los Vegas, and others with large inventories of foreclosed properties and high levels of unemployment.

"Large supplies of foreclosed properties will continue to be the biggest downside risk for home prices and metro area housing markets," said David Stiff, Fiserv chief economist. He said that in markets that were particularly affected by the housing bubble and subsequent crash, an irregular supply of foreclosed properties will cause prices to bounce around their lows for years to come.

Data from the study found that reduced home prices and low mortgage rates have reduced the price of home ownership to pre-bubble levels, luring many potential buyers into the market. At the same time, the fact that many households can no longer qualify for a mortgage is keeping a lid on demand.

Looking ahead, some of the nation's strongest housing markets are predicted to be in the Northwest, with healthy gains predicted over the next two years for Tacoma, Spokane, Eugene and other metropolitan areas in Washington and Oregon.

Florida and California present mixed bags, with most areas expected to show price declines through the third quarter of 2010, followed by gains the following year. In Florida, 10 percent gains in 2012 are foreseen for Ocala, Palm Bay/Titusville and Panama City, following small declines, while prices in the Miami, Ft. Lauderdale and Orlanda areas are expected to continue to show significant declines.

In California, most markets are expected to show declines in double or high single digits through the third quarter of 2010, followed by moderate growth over the following 12 months. The nation's biggest rebound is expected to take place in the Napa Valley region, with a 15.8 percent price appreciation predicted next year, following a 4.7 percent decline in the current one.

The study is based on data from the Fiserv Case-Shiller home price indexes of 375 U.S. metropolitan areas and from the Federal Housing Finance Agency. For purposes of the report, the current year covers the period of the third quarter of 2010 through the second quarter of 2011; the next year begins with the third quarter of 2011.