Microsoft Corp. (Nasdaq: MSFT) says Chief Research and Strategy Officer Craig Mundie plans to retire in 2014 after two decades and has shifted to a new role as a senior adviser to Chief Executive Officer Steve Ballmer.

Eric Rudder, Chief Technical Strategy Officer, is taking over some of Mundie’s duties overseeing research, privacy and security, as well as technology policy, Ballmer said in an e- mail to staff on Dec. 14 that Microsoft, the world’s largest software maker, made public today.

Mundie’s job switch marks the second change to Microsoft’s senior leadership team within the past two months. On Nov. 12, the company announced that Windows chief Steven Sinofsky was leaving. After releasing the latest version of its flagship operating system in October, Ballmer is putting in place a new team to start planning the next upgrade to help Microsoft compete in a market that has shifted to mobile devices and computing over the Internet.

The team led by Rudder “continues to help shape the long- term technology-policy landscape in ways that will give our future products a clear path in the marketplace,” Ballmer wrote in the memo.

During his time at Microsoft, Mundie was responsible for Microsoft’s early efforts in software for handheld organizers, cars and televisions. He also developed technology policy in areas such as privacy and security, oversaw the Microsoft Research unit and the company’s technology policy relationships with governments such as China and Russia.

Rudder previously served as senior vice president for servers and tools and oversaw Microsoft’s relationship with software developers.