Activision/Blizzard Negotiations Were Sticky

Gamasutra has a piece up looking at the SEC filing that reveals a lot of the details of the Activision/Blizzard merger, including the fact that negotiations started in mid-2006.
Preliminary discussions took place from November 2006 to March 2007 between the two companies, before deciding to make formal offers in April 2007, which led to the first breakdown in negotiations.

Throughout May, both Vivendi and Activision made counter-offers for the structure of the merger and the share price paid for Activision stock, and after a two week break, "[Vivendi CEO Jean-Bernard] Lévy telephoned [Activision CEO Robert] Kotick to advise him that, due to the meaningful differences between the two companies' proposals and lack of any apparent progress, he did not think it made sense to continue discussions concerning a possible transaction at that time."

Four days later, an Activision committee came together to rethink its proposal, and made a new offer in early July, which Vivendi said was "generally acceptable".

In August, however, more negotiations were necessary to assure Vivendi that "Blizzard Entertainment would continue to be managed by its current management team," which led to a meeting some two weeks later between Kotick and Blizzard CEO Mike Morhaime.