Microsoft’s previous CEO, Steve Ballmer, has stepped down from the company’s board. Ballmer announced last year that he would retire as CEO as soon as a replacement was found. After several months, the board landed on Satya Nadella, who officially took over in February. But Ballmer kept his seat on the board after retiring. In an open letter to Nadella, which you can read below, Ballmer said he is leaving the board to concentrate on other activities like his new ownership of the LA Clippers. Ballmer told the LA Times that he’ll also be teaching a class at USC’s Marshall School of Business.