According to a report in the Wall Street Journal, Microsoft board members decided that Bill Gates needed to step down from its board last year while an investigation was underway.
The investigation was into the billionaire's prior romantic relationship with an employee that was deemed "inappropriate."
Gates resigned before the board's investigation was completed and at the time claimed he was doing so to focus on his philanthropy.
A spokesperson for Gates said, "There was an affair almost 20 years ago which ended amicably" and "his decision to transition off the board was in no way related to this matter."