The case sets up an early test of how Trump’s pick to chair the agency — Paul Atkins — would navigate potential clashes with the incoming president's allies.

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.