Home prices in 20 U.S. metropolitan markets dropped to a six-year low in August, a survey showed, Bloomberg reported.

The home values fell 4.4 percent for the year ending in August, according to the S&P/Case-Shiller home price index, which has data back to 2001.

The struggling housing market appears to have even further to fall, with the S&P/Case-Shiller results reinforcing the views of Federal Reserve officials and Treasury Secretary Henry Paulson. Near-record inventory levels are expected to keep pushing prices down, which may threaten consumer spending because homeowners will have less equity to borrow against.

“This is really the No. 1 risk: a sustained, sharp decrease in home prices really squeezing consumers,” said Meny Grauman, an economist at Scotia Capital Inc. in Toronto.

In a Bloomberg News survey, economists had predicted the index would drop 4.2 percent, according to the median of 11 estimates.

Home prices in the 20 cities surveyed declined 0.7 percent compared with July after a 0.4 percent drop the month before. Economists focus on the year-over-year changes because the survey’s figures are not adjusted seasonally.