Two of the world's largest computer games producers, Activision and Vivendi Games, have announced an $18.9 billion (£9.2 billion) merger.
France's Vivendi is the owner of Blizzard, the developer of the hugely-successful online role-playing game World of Warcraft.
The new company will be named Activision Blizzard and will remain listed on the Nasdaq exchange.
A statement from the two companies claimed the merged entity would be the world's "largest, most profitable pure-play video game publisher".
The union brings together the Guitar Hero, Call of Duty and Tony Hawk franchises with massively-multiplayer online adventure game World of Warcraft, which has more than nine million subscribers worldwide.
The companies say that the union creates the "most diversified and broadest portfolio of interactive entertainment assets in its industry".
Jean-Bernard Levy, Vivendi chief executive, said: "This alliance is a major strategic step for Vivendi and is another illustration of our drive to extend our presence in the entertainment sector.
"By combining Vivendi's games business with Activision, we are creating a worldwide leader in a high-growth industry," he continued.
"We are excited about the opportunities for Activision Blizzard as a broader entertainment software platform."
Robert Kotick, Activision chairman and chief executive officer, said the merger was a "pivotal moment" in the computer game industry's history.
"By combining leaders in mass-market entertainment and subscription-based online games, Activision Blizzard will be the only publisher with leading market positions across all categories of the rapidly growing interactive entertainment software industry and reach the broadest possible audiences," he explained.