WASHINGTON (AP) — The number of Americans who signed contracts to buy homes fell for the third straight month in September after the spring-and-summer peak buying season failed to entice new buyers.

The National Association of Realtors says its index of sales agreements fell 4.6 percent last month to a reading of 84.5.

A reading of 100 is considered healthy. The last time the index reached that high was in April 2010, the final month that buyers could qualify for a federal tax credit that has since expired.

Contract signings are usually a reliable indicator of where the housing market is headed. There's typically a one- to two-month lag between a contract and a completed deal.

But the Realtors group said a growing number of buyers have canceled contracts.