Sales of existing U.S. homes fell unexpectedly in August after four consecutive months of gains, providing evidence that the recovery in the housing market remains fragile. The National Association of Realtors (NAR) reported Thursday that existing-home sales fell 2.7 percent last month to an annual rate of 5.1 million units, down from July's rate of 5.24 million. Economists had expected August sales to rise to a rate of 5.35 million. Despite the decline in sales, they are still up 3.4 percent from a year ago. One-third of existing-home sales last month were to first-time buyers, reflecting the November 30 expiration of a federal government incentive program. Existing-home sale are up almost 14 percent from the bottom seen in January, but they are still down nearly 30 percent from the peak four years ago. For the housing market to stabilize, sales would nee to increase to a pace of 5.5 million to 6 million per year, NAR chief economist Lawrence Yun said. If buyers see clear evidence of stable prices, the housing-market recovery can be self-sustaining, Yun said, adding “We are not there yet.”