The pending home sales index, a measurement based on home contracts that have been signed, fell in May to its lowest level in six years, according to the National Association of Realtors.

The national index was 97.7 in May, down 3.5 percent from April and 13.3 percent from May of last year.

Housing activity continued to be affected by tighter lending criteria for mortgages and a lack of buyer confidence, according to Lawrence Yun, NAR senior economist.

“Some transactions are being postponed from mortgage market disruptions,” he said.  “But better supervised lending will put housing in a fundamentally healthier state over the long term.”

Pending home sales rose 5.6 percent in the West to 95.4, but the index still is 13.7 percent below a year ago. In the Northeast, the index increased 3.8 percent from April to 93.1 but is 9.6 percent lower than May 2006. The index in the South fell 7.6 percent in May to 107.2 and was 15.4 percent below a year ago. In the Midwest, the index dropped 8.9 percent in May to 89.4 and was 11.7 percent below May 2006.