The SEC filed a lawsuit against Elon Musk on Tuesday, alleging the billionaire committed securities fraud in 2022 by failing to disclose his ownership in Twitter and buying shares at “artificially low prices.”

Musk, who is also CEO of Tesla and SpaceX, purchased Twitter for $44 billion, later changing the name of the social network to X. Prior to the acquisition he’d built up a position in the company of greater than 5%, which would’ve required disclosing his holding to the public.

According to the SEC complaint, Musk didn’t follow disclosure rules, “allowing him to underpay by at least $150 million for shares he purchased after his financial beneficial ownership report was due.”

The SEC had been investigating whether Musk, or anyone else working with him, committed securities fraud in 2022 as the Tesla CEO sold shares in his car company and shored up his stake in Twitter ahead of his leveraged buyout. Musk said in a post on X last month that the SEC issued a “settlement demand,” pressuring him to agree to a deal including a fine within 48 hours or “face charges on numerous counts” regarding the purchase of shares.

This story is developing.