U.S. home prices fell 6.3 percent in May from a year earlier as foreclosures weigh down values and purchases slump.

The decline was led by a 9.9 percent decrease in the region that includes California, the Federal Housing Finance Agency said today in a report from Washington. The second-largest drop was 9.2 percent in the area that includes Nevada and Arizona.

Foreclosures have boosted the supply of available homes and reduced prices because the properties sell at a discount. Low interest rates have done little to stimulate demand for homes as mortgage standards tighten and an unemployment rate near 9 percent reduces the amount of eligible buyers.

Prices rose 0.4 percent from April, the FHFA said. Economists had projected a 0.1 percent increase from the previous month, according to the average of 14 estimates in a Bloomberg survey.

Today’s FHFA report is based on repeat-sales data that compares prices of the same properties over time. The regulatory agency, which measures sales of homes with mortgages backed by Fannie Mae or Freddie Mac, doesn’t provide a specific price.

The median price of a home sold in May, the period covered by the FHFA report, was $169,300, according to the National Association of Realtors.

In June, the median price was $184,300, the Chicago-based trade group said yesterday. Sales of existing U.S. homes fell last month to an annual pace of 4.77 million, the lowest level since November, according to the report.