Activision said Wednesday that the Delaware Court of Chancery said the deal required a vote by non-Vivendi stockholders after a shareholder sued.
Activision and Vivendi SA, a French media conglomerate that owns 61 percent of Activision, both said they intend to proceed.
“Vivendi and Activision Blizzard remain committed to a swift conclusion of the transaction and are considering all options with their lawyers in light of the court’s order,” Vivendi said in a statement.
In July, Vivendi announced it would sell most of its stake in Activision, the maker of “World of Warcraft” and “Call of Duty.” Activision itself would buy $5.83 billion worth of shares at $13.60 apiece while the investor group would purchase another $2.34 billion worth.
Vivendi would end up cutting its stake to 12 percent while the investor group would control 24.9 percent. The rest of the shares would be traded on the public stock market.
Shares of SantaMonica, Calif.-based Activision fell a penny to close at $17.15 before the company announced the delay.