Twitter's share price rose by more than 27% after Musk made his share purchase public on 4 April 2022, the SEC said. Musk ended up buying Twitter for $44bn in October 2022 and has since changed the platform's name to X. The complaint was submitted by the SEC to a federal court in Washington DC on Tuesday.

The SEC alleges Elon Musk violated federal securities law by failing to disclose his more than 5% stake in Twitter on time.

"Musk underpaid Twitter investors by more than $150 million for his purchases of Twitter common stock during this period," the SEC said.