Blizzard Entertainment is currently a division of another company called Vivendi Games. Vivendi Games is a company that is publically traded on the Paris stock exchange under the ticker symbol VIV. It is not publically traded in the USA.

Vivendi Games is buying out Activision, which IS traded in the USA under the ticker symbol ATVI.

After the two companies merge, they will be called Activision Blizzard and trade under the ticker symbol ATVI on the Nasdaq.