While on the surface betting exchanges offer the same betting opportunities as a The customer can 't determine the outcomes contained in the accumulators. A betting exchange is a marketplace for customers to bet on the outcome of discrete events. Betting exchanges offer the same opportunities to bet as a bookmaker with a few differences. You can buy (also known as "back") and sell (also known as "lay") the. Former champion jockey Kieren Fallon, two other riders and three other men have been acquitted of conspiracy to defraud. So what is Betfair?.