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.

A once leading candidate to replace Tim Cook as Apple’s CEO announced his retirement Tuesday. Chief Operating Officer Jeff Williams, who has worked at Apple for 27 years, will be replaced in a “long-planned succession” by Sabih Khan,

Apple COO Jeff Williams is retiring after 27 years. His exit marks another recent major leadership shift at the company.