The British online betting giant Betfair will begin offering parimutuel betting on races run at the New York Racing Association's Aqueduct racetrack beginning with the track's next live card on Wednesday.\nAn agreement between the two companies will allow Betfair customers to use their existing accounts to bet into Aqueduct's commingled parimutuel pools. The agreement is similar to deals Betfair has reached over the past month with Keeneland, Oak Tree, Woodbine, Hawthorne, and the Breeders' Cup, among other U.S. racing organizations.\nAqueduct opened last Wednesday. Its meet will run through early May.\nBetfair has begun striking the deals as it tries to build support for its betting exchange in the U.S. and improve its relationships with U.S. tracks, many of which have been wary of betting exchanges. Although many North American racetracks have had agreements to offer commingled betting on their races in the United Kingdom for several years through a variety of services, the wagering totals have never grown to significant levels.\nBetfair, which earlier this year bought the U.S. account-wagering and horserace broadcasting company Television Games Network, pioneered betting exchanges at the beginning of the decade. The service has 2.5 million accountholders, according to Betfair. U.S. customers are prohibited from opening an account with the company because of federal prohibitions on bookmaking. \nBetting exchanges allow customers to bet against each other on horse races and other sporting events. Betfair charges its customers approximately 5 percent of winning wagers as a commission on exchange bets, though the rate can vary widely depending on an account-holder's activity.\nDan Silver, a spokesman for NYRA, said the deal did not include provisions that would compensate NYRA for any exchange bets made by Betfair customers on the association's races. In that sense, the deal differs materially from the agreements with Keeneland and the Breeders' Cup, both of which included compensation provisions based on exchange wagering by Betfair customers. Del Mar Thoroughbred Club had a similar agreement in place for its 2009 meet. \nThough officials have not provided details of those compensation agreements, the deals are believed to be similar to Betfair's agreement with the British horseracing industry, in which Betfair contributes 10 percent of its commissions on winning horserace wagers to British racetracks. Officials of Del Mar and Keeneland have both said that exchange betting on their tracks this year was "minimal."\nIn the past, Betfair has allowed its customers to offer exchange betting on North American racetracks regardless of whether the company had agreements with the tracks.