UPDATE: Don Mattrick has been appointed CEO of Zynga, effective July 8, 2013, it's been confirmed.
ORIGINAL STORY: Don Mattrick, the president of Microsoft's Interactive Entertainment Business and Xbox chief, is to resign, the Wall Street Journal reports.
The report suggests that Mattrick is close to signing a new role with social game firm Zynga, "possibly as its CEO".
Mattrick's appointment "could be made as soon as today", the site reports, with confirmation expected at around 9pm BST. Zynga's shares have soared by 11 per cent following the initial report.
It's long been rumoured that Mattrick is set to leave the company, with online speculation suggesting that the Xbox president could have been set to replace ex-EA CEO John Riccitiello, who left the publisher in March.
Mattrick has headed up Microsoft's IEB department for almost three years, serving previously as senior vice president on Microsoft's gaming business. Prior to that, Mattrick acted as the president of worldwide studios at EA.
If true, Mattrick's departure will come just months before the launch of Microsoft's Xbox One, the successor to Xbox 360 due to release this November.
Speculation has now turned to Mattrick's possible successor as the head of Microsoft's IEB, with some suggesting that Microsoft Game Studios VP Phil Spencer could be set to take over.