1. A computer system for processing of trades in financial securities the computer system comprising: a processor device; main memory coupled to the processor device; and a computer readable medium storing a computer program product for processing of attributable security messages for individual securities that are assigned for processing by the securities processor from a plurality of securities that are traded on a securities trading system, the computer program product comprising instructions to cause the computer system processor device to: electronically validating an attributable security interest message placed by a market participant on a securities trading system to determine whether the attributable security interest message relates to an individual security assigned to be processed by the computer system securities processor, the security chosen from a plurality of securities traded on the securities trading system and to determine whether the attributable security message is eligible for matching; store the validated attributable security interest message in a queue; transfer the validated message from the queue into an order book that resides in a protected portion of the main memory of the computer system securities processor, the order book having a bid side and an offer side; and electronically matching the validated attributable security interest message in a first one of the bid and offer sides of the order book and one of previously-validated attributable security interest messages that reside in a second one of the bid and offer sides of the order book with the instructions to match having exclusive control over the order book.