ABSTRACT

In combination in a data processing system for making a trading market in at least one security in which the system proprietor is acting as principal; said system including means for receiving trade orders for at least one said security from system customers, said trade orders including fields identifying the stock to be traded and characterisation of the trade as a customer purchase or sale, and the number of shares for the transaction; means for retrieving and for storing operative bid and asked prices for said at least one security; means for entering and for storing order qualification parameters, said parameters and said stored prices determining which received orders and qualified for execution; means for storing data characterising position, cost and profit for said at least one security; qualifying means responsive to said received trade orders and said stored prices and order qualification parameters for qualifying a trade order for execution when the received trade order fields do not violate the stored prices and qualification parameters; means for executing each trade order qualified by said qualification means; and post-execution updating means for updating said position and at least one of said stored parameters upon execution of a trade order.