French group Vivendi is to sell half of its remaining stake in video game giant Activision Blizzard, the US company confirmed Wednesday. Close to 41.5 million Vivendi-owned shares in the video game publisher behind titles such as "Call of Duty" would be put up for sale with a closure date of May 28, Activision said. Activision stock closed at $20.87 on the New York Stock Exchange, putting the value of the Vivendi sale at $866 million. An Activision spokeswoman said Vivendi would retain 41,499,688 shares or approximately six percent of Activision Blizzard. The company would have another open window in 2015 in which they could sell the balance or a portion of their shares, the spokeswoman added.