Former Nokia CEO, Stephen Elop, is to leave Microsoft as part of a management shake-up announced by Microsoft’s CEO Satya Nadella. Elop, who was in charge of Microsoft’s mobile devices’ unit, will depart after a “designated transition period”.

“We are aligning our engineering efforts and capabilities to deliver on our strategy and, in particular, our three core ambitions,” Satya Nadella said in an email to Microsoft staff. “This change will enable us to deliver better products and services that our customers love at a more rapid pace.”

“Stephen and I have agreed that now is the right time for him to retire from Microsoft,” Nadella added. “I regret the loss of leadership that this represents, and look forward to seeing where his next destination will be.”

Elop will be replaced by OS chief Terry Myerson, who will head up the newly created Windows and Devices unit.

The 51-year-old Elop had been responsible for Lumia devices ever since Microsoft acquired Nokia’s handset arm for around $7 billion in 2013, in which he was a key player. He was also instrumental in Nokia adopting Microsoft’s Windows OS on its high-end smartphones back in 2011, and according to some industry pundits, he was tipped as the most likely successor to Steve Ballmer. That now seems unlikely to happen.

The former Nokia boss wasn’t the only high profile executive to lose his job in Microsoft’s reshuffle. Nadella also announced the departures of Mark Penn, VP of Strategic and Special Projects, Kiril Tatarinov, head of Microsoft’s Business Solutions and Eric Rudder, a 25-year-veteran employee and former VP of Advanced Strategy.