Signed contracts to purchase previously owned US homes rose modestly in April, indicating stabilization in the housing market, but the pace of buying still is weaker than a year earlier, an industry group reported Thursday. The National Association of Realtors (NAR) said its pending home sales index, based on contracts signed in April, increased 0.4 percent to 97.8. The increase was below economist expectations and remains 9.2 percent below its level a year earlier. Pending home sales are a measure of future home purchases. A one- or two-month lag usually exists between a signed contract and a completed sale. Home sales have suffered since last summer when the U.S. Federal Reserve (Fed) signaled it would soon reduce economic stimulus efforts, pushing mortgage rates sharply higher. Sales also have been limited because of higher home prices, a tight supply of houses for sale, and a severe winter. The modest April gain in pending home sales reflects the slight decline in mortgage rates and the economic rebound from the harsh winter.