Activision Blizzard does not publish games under its central name and instead uses its studios to publish games. In early 2010, the independent studio Bungie entered into a 10-year publishing agreement with Activision Blizzard. By the end of 2010, Activision Blizzard was the largest video games publisher in the world. read more
Activision-Blizzard is a publisher. It is the publishing company formerly known as Vivendi Games, which published studios like Blizzard and Sierra. Vivendi Games shares were converted into Activision shares, thus forming a new company of which Vivendi Universal immediately purchased 52%. read more
Their stock is managed as one entity for the company Activision-Blizzard, which technically owns both Activision and Blizzard. They're sister companies, not the same company. read more