Twitter's stock price rose 27 percent once Musk belatedly disclosed his stake, the lawsuit said. "During the period that Musk was required to publicly disclose his beneficial ownership but had failed to do so, he spent more than $500 million purchasing additional shares of Twitter common stock," it said.

Elon Musk is being sued by the U.S. Securities and Exchange Commission over his 2022 Twitter takeover. The agency alleges that the billionaire failed to disclose his ownership of Twitter stock in a timely manner, saving himself at least $150 million “at the expense of shareholders.”