(AP) -- Activision Blizzard Inc. said Tuesday that Jason West and Vince Zampella, executives at "Call of Duty" developer Infinity Ward, are no longer with the company.
Zampella had served as CEO at Infinity Ward, and West as chief technology officer, among other titles.
Activision also said it plans to form a new business unit around the "Call of Duty" franchise, focusing on online content and expanding the brand.
The shake-up comes a day after Activision said it was looking into breaches of contract and insubordination by two senior employees at its Infinity Ward studio.
Activision did not name West and Zampella in Monday's regulatory filing. But the filing said the company expected the "departure of key personnel" as a result.
Infinity Ward did not make every "Call of Duty" title. But it was behind the original game and the latest installment, "Call of Duty: Modern Warfare 2," which broke entertainment records last fall when it made $550 million in worldwide sales during its first five days. By January, it crossed the $1 billion mark.
Activision said Tuesday it plans to release a "Call of Duty" game developed by Treyarch this fall. That studio had been behind less successful games in the franchise.
The company also plans a new "Call of Duty" for 2011 from another studio.
Philip Earl, who currently runs Activision Publishing's Asia Pacific region, will head the Call of Duty business unit.
Activision Publishing executives Steve Pearce, chief technology officer and Steve Ackrich, head of production, will lead Infinity Ward on an interim basis, the company added.
Shawn Milne, an analyst with Janney Capital Markets, said while having the top developers leave the company is "a new risk."
"A greater risk would be whether or not the two heads end up taking more talent away from (Activision), or the whole team leaves," he said in a note to investors.
Still, he said that given Activision's compensation model - based on a franchise's profitability - "we would believe there would be no shortage of top development talent looking to work on such a valuable brand."
Shares of Santa Monica, Calif.-based Activision slid 2 cents to $10.79 in after-hours trading.
Explore further: Why the Sony hack isn't big news in Japan