Alpha Dog Games: mobile developer, known for MonstroCity and WraithBorne.
Vicarious Visions: Blizzard support studio.
Treyarch: primary Call of Duty developer, known for World at War, Black Ops.
Sledgehammer Games: primary Call of Duty developer, known for Advanced Warfare, WWII, Vanguard.
Raven Software: support team, supporting Call of Duty.
Radical Entertainment: support team, supporting Destiny.
King: mobile developer, known for Candy Crush.
Infinity Ward: primary Call of Duty developer, known for Modern Warfare, Infinite Warfare, Warzone.
High Moon Studios: support studio, supporting Call of Duty.
Digital Labs Entertainment: support studio.
Beenox: support studio, supporting Call of Duty and Crash Bandicoot.
Some material below in case the Judge denies the FTC’s Preliminary Injunction against Microsoft’s Activision Blizzard adquisition (aka Microsoft is allowed to close the deal in USA):