Home prices in May fell roughly 1 percent month-over-month and 15 percent or more year-over-year, according to the S&P/Case-Shiller Composite Home Price Indices released Tuesday morning.

Widely considered the leading indicator of home prices in the United States, the S&P/Case-Shiller Indices track the value of typical single-family homes sold in an index of 10 large metropolitan markets and an index of 20 large markets, based on repeat sales.

The index's 20-city composite shows a 15.8 percent decline in home prices from May 2007 to May 2008, and a 0.9 percent decrease compared to April 2008. The 10-city composite exhibits a 16.9 percent decrease in home prices from May 2007, and a 1.0 percent decrease month-over-month between April and May of this year.

But not all markets saw such drastic price declines. Dallas and Charlotte show three straight months of price increases, including 1.0 percent price increases during May. Still, both markets show price declines on a year-over-year basis, though the declines are far smaller than in other markets. Charlotte shows just a 0.2 percent decline in home prices since May 2007, while Dallas saw a 3.1 percent decrease over the same period.

Some individual markets have seen home prices fall 25 percent or more in the last 12 months, including Las Vegas (down 28.4 percent), Miami (off 28.3 percent), and Phoenix (a decline of 26.5 percent), according to the S&P/Case-Shiller Indices.

Since April, the worst performing cities are Miami (down 3.6 percent in the last month) and Las Vegas (with prices off 2.9 percent).

In a statement announcing the release of new data on Tuesday, S&P chairman of the index committee, David Blitzer said there was some sign of encouragement this month. “One possible bright spot is that seven MSAs, while still negative, showed some improvement in their annual figures over those reported last month,” Blitzer said. “Looking at the monthly statistics, seven of the 20 metro areas were positive for the May/April reading.”

The seven metro areas with home price increases over the last month are Atlanta, Boston, Charlotte, Dallas, Denver, Minneapolis, and Portland, Ore.

Ethan Butterfield is senior editor, business, at BUILDER magazine.

Learn more about markets featured in this article: Atlanta, GA.