Standing up to the SEC. Tesla CEO Elon Musk refuted allegations Thursday that his brother engaged in insider trading before selling about $100 million in shares of the automaker, The Financial Times reported. Musk's statement followed a Wall Street Journal report that the Securities and Exchange Commission is investigating whether Kimbal Musk knew before the selloff that his brother would poll Twitter users the next day about whether to sell 10% of his stake in the company. Tesla's stock fell after the poll, which was posted one day after Kimbal Musk offloaded 88.500 shares.