Standard & Poor's S&P/Case-Shiller Home Price Indices for August, released this morning, showed a 5% decline in single-family home prices in the 10-city index and a 4.4% drop in the index for 20 of the nation's largest metro markets.

The declines marked the 8th consecutive month of negative annual returns and the 21st consecutive month of decelerating returns. The decline in the 10-city index was the biggest drop since June of 1991, when the index fell by 6.3%.

"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 an economics professor at Yale. "Year-over-year and monthly price returns are continuing to either move deeper into negative territory or are experiencing persistent diminishing returns. 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. Only two metro areas ­ Denver and Detroit ­ showed improvement in their annual returns and even those were reports of slightly less negative numbers."

Tampa posted the biggest decrease in August with a double-digit annual decline of 10.1%, followed by Detroit, with -9.3% and San Diego with -8.3%. Eight of the 20 metro areas reported their lowest recorded annual returns ­ these cities are Cleveland, LasVegas, Miami, Minneapolis, Phoenix, San Diego, Tampa, and Washington D.C.

Five markets managed to eke out price gains, including Atlanta (+0.8%); Charlotte (+5.6%); Dallas (+0.5%); Portland (+2.8%); and Seattle (+5.7%).