Housing prices in the country's 10 largest cities fell 5% in August, the largest annual decline since the recession of 1991, according to the S&P/Case-Shiller home price index. "At both the national and metro area levels, the fall in home prices is showing no real signs of a slowdown or turnaround," said Robert J. Shiller, chief economist at MacroMarkets LLC and co-creator of the index. The 10-city composite's annual decline of 5% is the worst since June 1991. The steepest drop on record was an annual decline of 6.3% recorded in April 1991. A 20-city composite of the index recorded an annual decline of 4.4% in August, the group said. "Year-over-year and monthly price returns are continuing to either move deeper into negative territory or are experiencing persistent diminishing returns," Shiller said. "There is really no positive news in today's report, as most of the metro areas are showing declining or vanishing returns on both an annual and monthly basis," he added. "Only two metro areas -- Denver and Detroit -- showed improvement in their annual returns and even those were reports of slightly less negative numbers." Several metro areas came under significant pricing pressure in August. Tampa, Fla., surpassed Detroit as the worst-performer in the month, reporting an annual decline of 10.1%. Detroit followed with a 9.3% decline, and San Diego was next with an 8.3% drop. Eight of the 20 metro areas reported their lowest recorded annual returns: Cleveland, Las Vegas, Miami, Minneapolis, Phoenix, San Diego, Tampa and Washington, D.C. Builder stocks were lower Tuesday following the news. Toll Brothers ( TOL) dropped 35 cents, or 1.5%, to $22.59; Beazer ( BZH) was down 49 cents, or 4.1%, to $11.38; and D.R. Horton ( DHI) was slipping 30 cents, or 2.3%, to $12.83.