U.S. sales of existing homes fell 4.3% to a seasonally adjusted annual rate of 5.50 million in August, the lowest since August 2002, the National Association of Realtors reported yesterday. Sales in August were down 12.8% compared with August 2006. Economists surveyed by MarketWatch were expecting sales in August to fall to a 5.49 million pace. Inventories of unsold homes on the market rose by 0.4% to 4.58 million, representing a 10-month supply at the August sales rate. For single-family homes alone, the inventory represents a 9.8-month supply, the most since May 1989. The median sales price was 224,500, up 0.2% since August 2006. Single-family median prices were unchanged year-over-year at 223,900.