https://arstechnica.com/tech-policy/2022/04/lawsuit-musk-saved-143-million-by-illegally-waiting-to-disclose-twitter-stake/

Elon Musk is facing a shareholder lawsuit over his failure to reveal his investment in Twitter until 11 days after a deadline set by federal law.

Musk started buying Twitter stock in January and acquired more than 5 percent of all shares by March 14, the lawsuit said. Under US law, "Musk was required to file a Schedule 13 with the SEC within 10 days of passing the 5 percent ownership threshold in Twitter, or March 24, 2022," said the complaint filed yesterday in US District Court for the Southern District of New York.