Abstract: A transaction system, including a server for receiving bids for coupons at prices less than a predetermined value, each coupon representing an outcome of an event having more than two possible outcomes, the coupon having the predetermined value if that outcome occurs and no value if that outcome does not occur, and a transaction engine for generating bid data representing buy and sell bids for and against each outcome of the event on the basis of the received bids, and determining a match between received bids on the basis of the generated bid data.