Ruiz will immediately take a voluntary leave of absence and will be resigning from the company January 4, Globalfoundries said in a statement on Monday.
The statement, which said Ruiz submitted his resignation in September, did not state a reason for his decision.
Alan "Lanny" Ross, former chief executive of Broadcom Corp , will serve on an interim basis until a p
ermanent chairman has been appointed.
Ruiz was said to have passed on confidential information regarding AMD's spin-off of Globalfoundries to a hedge fund manager when he was AMD's CEO.
Shares of AMD, which owns a large but minority stake in the venture with Abu Dhabi investors, rose about 2.3 percent in premarket trading on Monday.