Home prices rose 1.3 percent March to April in both the 10-city and 20-city indexes, but fell 2.2 percent in the 10-city index and 1.9 percent in the 20-city index from April 2011, the report said.
Economist had expected an annual decline of 2.5 percent for the larger index.
"While still negative, this is an improvement," the report said. In March, the 10-city composite index dropped 2.9 percent and the 20-city composite fell 2.6 percent on an annual basis.
In a clear break from recent reports, in April, 19 of 20 cities monitored showed month-to-month price increases. Only Detroit posted a decline with prices dropping 3.6 percent.
The sharpest gains were posted by San Francisco (prices up 3.4 percent, Washington (up 2.8 percent), Phoenix (up 2.5 percent), Atlanta (up 2.3 percent) and Portland, Ore., (up 2 percent).
"It has been a long time since we enjoyed such broad-based gains. While one month does not make a trend, particularly during seasonally strong buying months, the combination of rising positive monthly index levels and improving annual returns is a good sign," said David Blitzer, chairman of the Index Committee at S&P Indices.