Activision Blizzard, that's a big company right there. And, technically, it's a merger. But things could have been so, so different. Instead of a union, it could have been a buy-out, with Activision originally interested in straight-up purchasing the WoW creators. Says Activision boss Bobby "What, Me Worry?" Kotick:

We talked about the opportunity to buy Blizzard and they were adamant that they loved the [videogame] business and were committed to it. They didn't want to sell the business but would entertain other ideas. They were struggling on the console side and needed to diversify into other parts of the business and recognized how difficult that would be independently, which is how we ultimately settled on this structure.

Ah, the structure where Blizzard execs get fat new paychecks while Activision gets a piece of WoW's cash flow? Everybody wins!

Activision tried to buy Blizzard before merging with Vivendi Games [Variety]