Read Memos From Tim Cook and John Ternus on Apple CEO Transition

John Ternus and Tim Cook

Photographers: Adam Gray, David Paul Morris/Bloomberg

After tapping hardware chief John Ternus to succeed Chief Executive Officer Tim Cook as the iPhone maker’s leader, Apple Inc. sent memos to staff from both executives explaining the move.

Cook, who took the CEO role from co-founder Steve Jobs in 2011, said now was the “right time” to make the transition, which takes effect on Sept. 1. Cook will stay with the company as executive chairman.