The Commerce Guild is a business conglomerate that was one of the corporate backers of the Confederacy of Independent Systems during the Clone Wars, and are an antagonistic faction in the Star Wars franchise.
The Commerce Guild was formed in at least 700 BBY from the merging of several major commerce entities. In the lead up to the Clone Wars, the Commerce was among the major corporate powers who pledged loyalty to the Confederacy of Independent Systems and as a result its Presidente Shu Mai was given a spot on the Separatist Council. The Commerce Guild supported the CIS in the war by supplying them with their Spider Droid models, the colossal Homing Spider Droids and smaller Dwarf Spider Droids.
At the end of the Clone Wars, the Commerce Guild was presumably regimented into the Galactic Empire along with most of the other major corporate bodies in the galaxy.