Apple CEO Tim Cook is about to take over one of the most significant parts of Apple’s business: its design team. The team currently reports to COO Jeff Williams, but once Williams begins his just-announced retirement “late in the year,” the design team “will then transition to reporting directly to Cook,” Apple says.

Apple’s chief operating officer plans to hand the role off this month and retire later this year after roughly a decade as the tech giant’s No. 2 under Chief Executive Tim Cook.

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.Williams will step down as COO this month before retiring from the company later in the year,