SAN FRANCISCO (Reuters) - Microsoft's entertainment head, Don Mattrick, is leaving the company to possibly join struggling games publisher Zynga as its chief executive, according to a report by AllThingsD on Monday, and Zynga shares shot up about 12 percent.

Don Mattrick, the president of Microsoft's Interactive Entertainment Business, who heads the company's gaming division and manages the Xbox business, is leaving the company to join Zynga, possibly as its CEO and "working in close partnership with its founder and current CEO Mark Pincus," the report said.

Zynga shares were up 11.5 percent at $3.10 in afternoon trading on the Nasdaq.

(Reporting by Malathi Nayak. Editing by Andre Grenon)