By Greg Robb
WASHINGTON (MarketWatch) -- Home prices rose 0.8% in April compared with March in 20 major U.S. cities, according to the Case-Shiller home price index released Tuesday by Standard & Poor's. This is the first increase after six straight monthly declines. Prices have moved up 3.8% in the past year. Prices rose in 18 of the 20 metropolitan areas tracked by Case-Shiller in April compared with March. The data are not seasonally adjusted.