What is the ticker symbol for Blizzard Entertainment?

Unfortunately, you cannot directly purchase stock in this American developer of popular PC games directly, because Blizzard Entertainment is a division of Vivendi SA.

In additional to owning Blizzard, Vivendi SA is a French media conglomerate that own many notable media outlets such as Universal Music Group and a 20% stake in NBC Universal.

Investing in Viviendi SA is possible in several ways it is traded on Euronext Paris stock exchange under the ticker symbol VIV and it is traded via the Pink Sheets in the US under the ticker symbol VIVDY or VIVDY.PK

This is partially true in that Vivendi does own the 52% majority of what was Blizzard. This was during the merger between Activision and Blizzard Entertainment forming what we now know as Activision Blizzard and 48% of the holdings stayed with the company in Santa Monica. They are ATVI on NASDAQ.