Abstract: A betting exchange system receiving bet requests from a plurality of users over a communications network, each of the requests comprising a bet backing an outcome or laying an outcome. The betting exchange system matches respective bets which back and lay a given outcome, and automatically arbitrages unmatched bet requests to thereby generate one or more implied bets made by the system in respect to an outcome for which no bet requests have been received. The implied bets are generated so that the system does not lose money on the implied bets taken together.

Abstract: A betting exchange system receiving a plurality of bet requests backing a given outcome, each backing bet request specifying a price and a size at which an originator of the request is prepared to bet that the given outcome will occur. The betting exchange system receiving a plurality of bet requests laying the given outcome, each laying bet request specifying a price and a size at which an originator of the request is prepared to bet that the given outcome will not occur. The betting exchange system aggregating backing bet requests specifying the same price, aggregating laying bet requests specifying the same price, automatically matching a received backing bet request with individual or aggregated laying bet requests to complete a betting transaction, and automatically matching a received laying bet request with individual or aggregated backing bet requests to complete a betting transaction.

Abstract: According to the present invention, there is provided a betting exchange system comprising server means configured to receive bet requests from a plurality of users over a communications network, each of said requests comprising a bet backing an outcome or laying an outcome, wherein the server means is operable to match respective bets which back and lay a given outcome. Allowing a user access to both sides of a betting transaction, by specifying whether he wishes to back or lay an outcome, provides the user with additional flexibility, and can facilitate a liquid two-way market. In addition, it can ensure the most efficient, and hence competitive, prices.