NEW YORK - December 29, 2010 - U.S. single-family home prices fell for a fourth straight month in October pressured by a supply glut, home foreclosures and high unemployment, data from a closely watched survey showed Tuesday.

The Standard & Poor's/Case-Shiller composite index of 20 metropolitan areas declined 1.0% in October from September on a seasonally adjusted basis, a much steeper drop than the 0.6% fall expected by economists.

The decline built on a revised decrease of 1.0% in September and took prices down 0.8% from year-ago levels. It was the first year-on-year drop in the index since January.

The housing market has been struggling since homebuyer tax credits expired earlier this year. To take advantage of the tax credits, buyers had to sign purchase contracts by April 30.

"The (housing) double dip is almost here, as six cities set new lows for the period since 2006 peaks. There is no good news in October's report,'' said David Blitzer, chairman of the index committee at S&P.

Eighteen of the 20 cities showed weaker year-on-year readings in October and all 20 cities showed monthly price declines.

Unadjusted for seasonal impact, the 20-city index fell 1.3% in October after a 0.8% decline in September.