Single-family home prices remained in freefall in July, according to the S&P/Case-Shiller Home Price Indices released Tuesday morning.

The Case-Shiller 10-city composite index sank 17.5 percent in July compared to a year ago, producing its tenth consecutive month of record declines. This index covers the metropolitan markets of Boston, Chicago, Denver, Las Vegas, Los Angeles, Miami, New York, San Diego, San Francisco, and Washington, D.C.   

Its broader counterpart, the Case-Shiller 20-city composite index, slipped 16.3 percent in July in year-over-year comparisons. This includes the markets mentioned above, plus Atlanta, Charlotte, Cleveland, Dallas, Detroit, Minneapolis, Phoenix, Portland (Ore.), Seattle, and Tampa.

"There are signs of a slowdown in the rate of decline across the metro areas, but no evidence of a bottom," said David M. Blitzer, chairman of the Index Committee at Standard & Poor's, in a statement. "Little positive news can be found when cities like Las Vegas and Phoenix report annual declines as large as minus 29.9 percent and minus 29.3 percent, respectively, and all 20 cities are still in negative territory on a year-over-year basis."

"The Sunbelt continues to be the story," Blitzer continued, "with the seven cities that basically represent that area reporting annual declines roughly between 20 percent and 30 percent. While some cities did show some marginal improvement over last month's data, there is still very little evidence of any particular region experiencing an absolute turnaround."

Las Vegas remains the weakest market, reporting an annual decline of 29.9 percent, followed by Phoenix and Miami at -29.3 percent and -28.2 percent, respectively. Atlanta, Dallas, Minneapolis, and Tampa showed improvements in their annual and monthly returns, but all four are still too close to their recent lows to determine if the markets have stabilized, S&P said. While their annual returns are negative, Atlanta, Boston, Dallas, Denver, and Minneapolis all reported positive returns for the three months or more.

For more detail on the Case-Shiller indices, click here.