Jeff Williams has been Apple's Chief Operating Officer since 2010, but he's begun his retirement process and will be passing the reins to Sabih Khan.

Apple's COO Jeff Williams steps down, with Sabih Khan taking over. This planned succession marks a significant leadership change.

Sabih Khan, Apple's senior vice president of operations, will assume the COO role later this month as part of what Apple called a long-planned succession. Williams will continue reporting to CEO Tim Cook in the interim while overseeing the Apple Watch,