According to a statement from a Tesla spokesperson, "This week Elon increased his investment in Tesla. He exercised and held 532,000 stock options, which is approximately $100 million in current value. Elon did not sell any shares even though he had to pay more than $50 million of taxes in connection with the exercise. Instead of selling, he used cash to pay both the taxes and the exercise price."
Thanks to the SEC filing of the transaction, the initial price of those half-million stock options was $6.63 each. What that means is that, since the TSLA stock is now trading at $191.20, Musk could have sold sold them to make around $98 million. Instead, he held onto the stocks - paying $50 million in taxes out of other funds – to own more of his own company. According to TechCrunch, Musk now owns about a fifth of Tesla Motors. The Los Angeles Times reports that Musk owns 29 million shares, which is about 22 percent of the total. TSLA was trading at over $240 a month or so ago, which prompted some trading sites to say that Musk bought his shares for, "cheap."
The move comes before Tesla reports its fourth-quarter earnings on February 10 and unveils its lower-cost, 200-mile EV, the Model 3, at some point in March, but not at the Geneva Motor Show.