French media conglomerate Vivendi once owned a majority stake in Activision Blizzard, but soon will own less than 6 percent of the company -- after it offers 41.5 million shares of Activision Blizzard stock in a public sell-off.Activision Blizzard and Vivendi announced plans to part ways last July, when the video game company instituted a stock buyback program to capture a large part of Vivendi's shares. CEO Bobby Kotick also lead a cohort of investors, including Chinese publisher Tencent, to buy another swath of the video game company's shares.The 41.5 million shares Vivendi is selling represent half of its current stake in the company, which after this latest sale will be down to 5.8 percent. Bloomberg Businessweek points out that this sale will be worth about $866 million at today's stock price.