Bill Gates last week ceded his title as Microsoft's largest individual shareholder to former CEO Steve Ballmer. It was the first time in Microsoft's nearly 40 years that Gates, 58, was not the company's top shareholder.Gates, who co-founded Microsoft in 1975, served as CEO until 2000 and only stepped down as chairman in February, sold a total of 7.85 million shares in transactions on April 29 and 30, according to documents filed with the U.S. Securities and Exchange Commission (SEC).