This paper discusses a modern market management system architecture that was developed from the ground up with a view to being open, service oriented, standards based, and using commercially available components wherever possible. The design principles that were used in developing this modern MMS system and experiences gained from many years of commercial operation around the world. The resulting market management system (MMS) became the very first integrated web based multi-tiered system that supported both market participant transaction processing as well as the execution of advanced market scheduling applications such as security constrained unit commitment (SCUC). This modern MMS embraces standards such as XML, JMS, and Web services. It has the native features necessary to provide a meaningful service oriented platform, readily adopt new technological innovations and standards, and conform to directions set by the electric energy industry.