This is the biggest single change since Tesla's 2010 IPO and when complete the departures would shrink its 11-member board to seven people, including Musk and his younger brother Kimbal and clean-tech investor Ira Ehrenpreis. In late December, the company added billionaire Larry Ellison and Kathleen Wilson-Thompson, an executive with the Walgreens Boots Alliance, as independent board members to fulfill a settlement with the SEC over Musk's tweets about taking the company private. He also lost his position as Tesla board chairman, a position taken over by board member Robyn Denholm.