Vivendi Games finalized a merger with "Guitar Hero III" publisher Activision over the weekend, creating a massive new videogame company called Activision Blizzard.

Vivendi will own the majority stake in the newly formed company, which is valued at about $18.9 billion. Activision CEO Robert Kotick will lead the new company, while Vivendi Games CEO will serve as vice chairman and chief corporate officer.

Vivendi Games owns Blizzard Entertainment, which develops the popular online multiplayer role playing game World of Warcraft. The game counts more than 9 million monthly subscribers. It also owns U.S. game publisher Sierra Entertainment.

The implications of this merger to the music industry are not yet fully clear. Vivendi is also parent company to Universal Music Group. While no formal relationship is in place, the games division does enjoy easier access to UMG music content, perhaps best exemplified by the game “50-Cent: Bulletproof.” The game contained many music-related extras including many music videos, extra songs and more.

UMG head Doug Morris will sit on the board of the newly formed company, suggesting there will be some level of collaboration going forward. Activision’s “Guitar Hero III: Legends of Rock,” release in late October, is emerging as one of the best-selling games of the year with 1.4 million units sold in the first six days after its release. The game also allows users to buy new music that they can download into the game as additional playable levels.