Home prices in 20 U.S. cities fell 18.2% in November from a year earlier, the fastest drop on record, as foreclosures climbed and sales sank, according to a report released Tuesday.

The decline in the S&P/Case-Shiller index was in line with forecasts and came after an 18.1% drop in October.

The gauge started falling in January 2007; year-over-year records began being kept in 2001.

"The housing market has not yet reached its bottom," said Neal Soss, the chief economist at Credit Suisse Holdings in New York. "People have to be in a position where they are not afraid of their most significant asset."

Economists had forecast that the 20-city index would fall 18.4% from a year earlier, according to the median of 27 estimates given in a Bloomberg News survey.

The estimates ranged from declines of 17.4% to 20%.

Compared with a year earlier, all areas in the 20-city survey showed price declines in November, led by a 33% drop in Phoenix and a 32% fall in Las Vegas.

"The free fall in residential real estate continued through November," David Blitzer, the chairman of the index committee at Standard & Poor's Corp., said in a press release. "Overall, more than half of the metro areas had record annual declines," he said.

Robert Shiller, the chief economist at MacroMarkets LLC and a professor at Yale University, and Karl Case, an economics professor at Wellesley College, created the home-price index based on research from the 1980s.

S&P publishes the index in partnership with MacroMarkets and Fiserv Inc., which bought Case Shiller Weiss Inc. in 2002.

The 20-city index is down 25% from its 2006 peak.

Eleven of the 20 metropolitan areas showed record declines in the year ended in November, and eight showed the biggest month-to-month decrease on record.

Home prices fell 2.2% in November from the prior month, matching the October decrease, the report showed.

The figures are not adjusted for seasonal effects, so economists prefer to focus on year-over-year changes instead of month-to-month.

Phoenix and Las Vegas also showed the biggest one-month declines.

Other housing reports have shown property values continuing to weaken as foreclosures rise.

The median sale price of an existing home fell 15.3% in December from a year earlier, compared with a 13.6% annual decline the previous month, the National Association of Realtors said Monday.

Sales of existing homes, about 90% of the market, gained 6.5% in December from a decade-low level the prior month, the Realtors group said.

For all of last year, existing-home sales fell 13.1%.

U.S. foreclosure filings jumped 81% last year as more than 2.3 million properties got a default or auction notice, or were seized by lenders, according to RealtyTrac Inc., an Irvine, Calif., seller of default data.

"The decline has accelerated over the past few months due to the increase in deeply discounted foreclosure sales," Michelle Meyer, an economist at Barclays Capital Inc. in New York, said before the S&P/Case-Shiller report was released. "The decline in the housing market worsened markedly at the end of last year."

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