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

Since joining Apple in 1995, Sabih Khan played a key role in delivering each of Apple's innovative products to market.

A bombshell announcement from Cupertino late on Wednesday is reshaping the highest echelons of leadership at Apple, the world’s most valuable and scrutinised corporation. Jeff Williams, the Chief Operating Officer for the past decade and a figure many considered a potential,