The nation’s largest video game publisher has shuffled its senior management team and realigned its internal structure without telling investors or the public.

Santa Monica-based Activision Blizzard Inc. has divided itself into four units, with one focused on the military video game Call of Duty, another handling other company-owned titles such as Guitar Hero and the Tony Hawk skateboarding games, and a third handling licensed properties, according to internal memos.

Blizzard Entertainment, maker of the successful online game World of Warcraft, remains an independent unit. Among executives reshuffled was Mike Griffith, who formerly oversaw all of Activision’s business except Blizzard. He has been named vice chairman and will serve as advisor to Chief Executive Bobby Kotick. The company also laid off about 15 employees as part of the shake-up.

It’s the first major shake-up for the company since Activision merged with Vivendi Games in 2008 to create Activision Blizzard.

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