The Securities and Exchange Commission has filed a lawsuit accusing Tesla boss Elon Musk of securities fraud.
The US financial regulator says Mr Musk’s claims that he had secured funding to take the electric carmaker private were “false and misleading”.
They led to confusion in the stock market and harmed investors, according to the complaint.
The SEC is seeking to bar Mr Musk from acting as an officer or director of a publicly traded company.
It is also seeking financial penalties.
Mr Musk startled the business world last month when he took to Twitter to announce that he was considering a plan that would de-list the company from the stock exchange.
He wrote he had “funding secured” for the plan, which would value Tesla at $420 per share.
The statements “created the misleading impression that taking Tesla private was subject only to Mr Musk choosing to do so and a shareholder vote”, according to the SEC complaint.
“In truth and in fact Musk had not even discussed much less confirmed key deal terms, including price, with any potential funding source,” it says.
Mr Musk is co-founder of Tesla and has served as chief executive since 2008.
The lawsuit was filed on Thursday in a federal court in Manhattan.
It sent shares of the firm down more than 10% in after-hours trade.