A system in an electronic securities market includes a configurable look-up table that has assignment entries that assign each of a plurality of securities to one or more securities processors in the system. Whenever an order is received that involves a specific security, a security look-up process accesses the configurable look-up table to determine which securities processor the specific security is assigned to. Once determined, a messaging process, which is responsive to the security look-up process, sends the received security order to the securities processor to which the specific security is assigned.