Musk is trying to appeal the finding, saying in a filing Friday that the judge “parsed the individual phrases of the various tweets and indicated certain other information should have accompanied the tweets, even though the short-form Twitter medium limits the number of characters per tweet.”

Musk’s lawyer, Alex Spiro, didn’t respond to a request for comment on the SEC fight, which is ongoing in New York. But his response to Chen’s ruling on April 16 was defiant.

“Nothing will ever change the truth, which is that Elon Musk was considering taking Tesla private and could have,” the attorney said.

Columbia’s Gordon said the Tesla CEO isn’t helping himself by continuing to defend the tweet.

“Musk’s subsequent denialism in the face of Judge Chen’s ruling will further weaken his case against the SEC,” he said.

Not all securities experts agreed Chen’s ruling was so potentially damaging. James D Cox, a professor at Duke Law School, said the SEC faces an uphill fight trying to apply a ruling from a San Francisco lawsuit to a New York case involving different parties.

Going forward, the challenge facing the SEC is how to regulate high-profile public figures like Musk with millions of Twitter followers, with these VIPs knowing the potential impact of their statements on capital markets, said Jill E Fisch, a professor at the University of Pennsylvania Law School.

“Musk is the current and most visible example of this,” Fisch said. “He’s not likely to be the only one.”

The SEC declined to comment.

As for Musk’s other legal woes, he’s awaiting a ruling any day following a $US13 billion trial in Delaware over his role in the electric-car maker’s 2016 buyout of SolarCity.

In the San Francisco case, Bloomberg Intelligence estimated before Chen issued his ruling that the lawsuit could settle for between $US260 million and $US380 million.

“The price of settlement just went way up,” said Adam C Pritchard, a professor at the University of Michigan Law School. Chen’s ruling was a “huge win” for shareholders and an appeal of the decision by Musk “might be hard to come by,” he said.

Nicholas Porritt, a lawyer representing shareholders, said he expects Chen’s ruling will soon become public.

Chen’s decision means that Musk won’t be able to argue to jurors that some key statements in his tweets were true, or that he didn’t act fraudulently when he made them, Porritt said.

A pretrial ruling that so thoroughly discredits a defendant in a securities fraud case is “very rare,” Porritt said. “Certainly it has not been obtained in any case of similar size to this one.”