Elon Musk Is Having a Really Bad Day by Kia Kokalitcheva @FortuneMagazine February 10, 2016, 5:43 PM EDT E-mail Tweet Facebook Linkedin Share icons Public tech companies as a whole are having a bad week, but entrepreneur Elon Musk is having an especially bad day. Musk, who first rose to success as a co-founder of PayPal PYPL , is currently the largest shareholder in electric carmaker Tesla TSLA , as well as solar panel company SolarCity SCTY . Thanks to significant stock price drops for both companies today, Musk lost a total of $296.6 million, on paper, by the close of the market on Wednesday. Tesla, which Musk co-founded and currently leads as the company’s CEO and chairman, saw its price drop by 3.1%, from $150.50 per share to $143.67. According to a company filing to the SEC from January 27, Musk owns 28.9 million shares, or a 22% stake. As for SolarCity, co-founded by Musk’s cousins Peter and Lyndon Rive and of which he’s the chairman, it saw its price drop by 29.3% by the end of Wednesday. It opened at $19.42 and closed at $18.63. Musk owns a 22% stake in the solar panel company, or 21.275 million shares, according to an SEC filing from January 4. Musk’s day got better after the close; Tesla shares were up 11% in after-hours trading despite results that missed expectations. With that said, Musk’s net worth is estimated to be around $10.5 billion, according to Forbes‘s most recent math. He also has SpaceX, his private space exploration company, which recently successfully landed a reusable rocket after several failed attempts.