Beginning Oct. 1, Betfair will no longer accept exchange wagers from its New Jersey customers, ending a brief and unsuccessful experiment in the U.S. for a form of wagering that couldn't overcome a number of obstacles that stood in its way of success. Founded in 2000, Betfair introduced exchange wagering in the U.K., where it proved to be wildly popular. A betting exchange is a marketplace where customers set their own odds on a horse. If someone accepts those odds, the bets are matched. This also allows customers to act...