https://arstechnica.com/cars/2018/09/elon-musk-settles-fraud-charge-he-and-tesla-to-pay-40-million-in-penalties/

Elon Musk reached a settlement today with the Securities and Exchange Commission on a charge of securities fraud. Within the next 45 days, Musk will have to step down as chairman of Tesla and will be ineligible to return to that post for the next three years. However, Musk can continue in his role as the company's CEO. Additionally, Tesla was charged with "failing to have required disclosure controls and procedures relating to Musk’s tweets"—a matter which it promptly settled.

In August, Musk tweeted that he was taking the car maker private, and had "funding secured" to do so at the price of $420 a share. The result was a significant spike in Tesla's share price that was then reversed when it turned out that there was no such funding, nor much possibility of taking Tesla private under the circumstances Musk had promised.