Activision and Vivendi have made a surprise announcement today, revealing they have merged together to form the world's largest games publisher.

Previously, the biggest games firm was Electronic Arts, but the new $18.9 billion dollar firm, which will be called Activision Blizzard, has now taken over the crown.

The new company, which owns a raft of titles including Warcraft, Diablo, Guitar Hero, Call of Duty, Tony Hawks, James Bond, Spider-Man and Shrek, can now lay claim to enjoying "the most diversified and broadest portfolio of interactive entertainment assets in its industry".

Jean-Bernard Levy, chairman of the management board and CEO of Vivendi, 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. We are excited about the opportunities for Activision Blizzard as a broader entertainment software platform."