Patent ID: 7873544

Claim:
A method comprising: (a) providing a market center order book having limit orders posted thereon, wherein the limit orders posted on the market center order book each have a trading firm identifier and system timestamp parameter; (b) receiving by a computing system an incoming order having a first trading firm identifier and a first anti-internalization parameter; (c) determining by the computing system whether the incoming order is an anti-internalization order; (d) responsive to determining that the incoming order is an anti-internalization order, setting the first anti-internalization parameter to active; (e) responsive to determining that the incoming order is not an anti-internalization order, setting the first anti-internalization parameter to inactive; (f) retrieving by the computing system the best contra-side limit order to the incoming order from the market center order book, wherein the best contra-side limit order has a second anti-internalization parameter and a second trading firm identifier; (g) determining by the computing system whether the incoming order is marketable against the best contra-side limit order; (h) responsive to determining by the computing system that the incoming order is marketable against the best contra-side limit order: (h)(i) determining by the computing system whether both the first and second trading firm identifiers indicate that the incoming and best contra-side limit orders were posted by the same trading firm; (h)(ii) responsive to determining that both the first and second trading firm identifiers indicate that the incoming and best contra-side limit orders were posted by the same trading firm: (h)(ii)(a) determining by the computing system whether the first and second anti-internalization parameters are set to active; (h)(ii)(b) responsive to determining that both the first and second anti-internalization parameters are set to active, cancelling by the computing system the order with the most recently set system timestamp parameter; (h)(ii)(c) responsive to determining that both the first and second anti-internalization parameters are set to inactive, matching by the computing system the incoming and best contra-side limit orders; (h)(ii)(d) responsive to determining that the first anti-internalization parameter is set to active and the second anti-internalization parameter is set to inactive, cancelling by the computing system the incoming order; and (h)(ii)(e) responsive to determining that the second anti-internalization parameter is set to active and the first anti-internalization parameter is set to inactive, cancelling by the computing system the best contra-side limit order.