Abstract: A computer implemented trading system is described comprising a plurality of buy computers (1,2) connected via a communications network (3) to a plurality of seller computers (4,5), a plurality of public exchange computers (6,7) and a trading platform computer (8). The trading platform computer (8) is arranged to receive order data from the buy computers (1,2) and the seller computers (4,5). An order processing system (14) provided on the trading platform computer (8) processes the received data to generate output data indicative of the orders received by the order processing system (14) but which is processed so as to obscure the detail of received orders. The generated data is then dispatched back to the buyer computers (1,2) and seller computers (4,5) where it is displayed as part of a user interface.