ValueAct got onto the Microsoft board after its CEO Jeffrey Ubben had agitated for a seat on the board. At an investor conference last year, Ubben called on Microsoft to make Office more widely available on non-Windows platforms including the iPad and Google’s Android.
As of February, ValueAct owned less than 1% of Microsoft.
“We’ve had the opportunity to work with Mason over the past six months, and we look forward to working with him more closely as a member of the board,” said John Thompson, Microsoft’s chairman, in a statement Tuesday. “Mason brings valuable insights given his financial background, his extensive experience as a public company director and his perspective as a significant Microsoft shareholder.”