According to the Case-Shiller price index, which was released by Standard & Poor's this morning, U.S. home prices dropped 4.5% in the year covered from last year's third quarter to this year's third quarter. Compared to the second quarter, prices dropped 1.7%. This quarter-to-quarter drop is the largest price decline in the 20 years covered by the index. In the year ending in the second quarter, prices dropped 3.2%. In all 20 major cities covered by the index, the price dropped in September compared to August, and were down 4.9% in the past year. Prices dropped 5.5% on a year-over-year basis in the original 10-city index. The Case-Shiller index tracks multiple sales of the same homes and is considered by many observers to be the best gauge of national and metropolitan-area real-estate values.