Apple says COO Jeff Williams will retire later this year, and Sabih Khan, Apple's SVP of Operations, will take over much of his role later this month (Mark Gurman/Bloomberg)

Mark Gurman / Bloomberg:
Apple says COO Jeff Williams will retire later this year, and Sabih Khan, Apple's SVP of Operations, will take over much of his role later this month  —  Apple Inc. Chief Operating Officer Jeff Williams is retiring as the company's longtime No. 2, marking a major changing of the guard at an already tumultuous time for the iPhone maker.