Tesla CEO Elon Musk appears to have violated federal law by not notifying the SEC that he was buying up shares of Twitter, according to a report.

SEC regulations required Musk to notify the market when his stake in the social media company had surpassed the 5% threshold — a delay that reportedly netted him a profit of $156 million, according to The Washington Post.

Musk shocked the world when it was learned on Monday that he acquired a 9% stake in Twitter — making him the company’s largest shareholder.

Musk’s investment in Twitter had reached 5% on March 14, but the markets weren’t told of his acquisitions until Monday, when disclosure forms were made public. By failing to notify investors, Musk kept the stock price low as he continued to buy up shares.

After Musk filed his disclosure forms, Twitter’s share price skyrocketed by some 30%.

“I really don’t know what’s going through his mind,” finance professor David Kass of the University of Maryland told The Washington Post. “Was he ignorant or knowledgeable that he was violating securities law?”

Experts told the paper that Musk may have also misled the public when he filed forms indicating he would be a “passive investor” — particularly in light of Twitter’s announcement that he would be joining the board of directors.

The Post has reached out to Musk and the SEC seeking comment.

Don’t expect Musk, 50, to be arrested or serve any time in prison, according to experts.

The SEC will likely impose a six-figure fine on the world’s richest person, whose net worth has been pegged at around $280 billion — nearly $100 billion more than No. 2 on the list, Jeff Bezos.

Musk has locked horns with the SEC in the past — most famously over the mogul’s misleading tweet from Aug. 7, 2018 that claimed he had secured funding to take Tesla private at $420 a share — a price he later said was a pot joke to impress his then-girlfriend Grimes.

Last month, the SEC filed documents in Manhattan federal court reminding Musk that he was bound by an agreement to have any tweets related to his ownership of Tesla vetted before posting.

The SEC also rejected what it called Musk’s “substantively meritless” motion to quash a subpoena requesting records concerning his Twitter poll last November over whether to sell some of his Tesla stock.

Tesla said that this past November, the SEC sought “information on our governance processes around compliance” with a September 2018 settlement between the company and the regulatory agency.

The subpoena was issued just 10 days after Musk triggered a stock sell-off when he asked his Twitter followers if he should sell 10% of his stake in the company.

Tesla’s stock price dipped by some 16% over the course of the two days of trading that followed the tweet.