The nickname "Teflon Musk" was earned by the CEO of the company. His run of personal victories may be in danger.
Last week, it was revealed that a San Francisco judge had determined that one of Musk's statements about taking his company private was a lie.
It's one of at least a dozen high-profile cases that Musk has been involved in in the years after he posted the famous "funding secured" message.
The consequences of his previous use of the social media platform may come back to haunt him as he ramps up his battle to buy the company.
The judge's decision is in favor of the investors who are trying to recover billions of dollars in trading losses they blame on Musk's go-private message. A jury trial is set for January.
The decision poses a threat to Musk's effort to unleash himself from oversight by the SEC, a quest so personal for the world's richest person that he became emotional while lambasting the agency during a TED talk in Canada last week.
Securities law experts, including Columbia Law School professor Jeffrey Gordon, say that being ruled a liar will make it harder for the voluble billionaire to wriggle out.
Musk said in a sworn statement in New York federal court that he never lied to shareholders.
That was before the ruling of the U.S. District Judge Edward Chen in San Francisco was made public.
Musk is trying to appeal the finding, saying in a filing Friday that the judgeparsed the individual phrases of the various tweets and indicated certain other information should have accompanied the tweets.
Alex Spiro, Musk's lawyer, didn't respond to a request for comment on the SEC fight. His response to Chen's ruling was defiant.
The attorney said that the truth was that Musk was considering taking the company private.
Gordon said the CEO isn't helping himself by defending the post.
He said that Musk's subsequent denialism in the face of Judge Chen's ruling will further weaken his case against the SEC.
Not all securities experts agreed with Chen's ruling. James D. Cox, a professor at Duke Law School, said that the SEC faces an uphill fight trying to apply a ruling from a San Francisco lawsuit to a New York case.
The SEC faces a challenge in regulating Musk and other high-profile public figures with millions of followers on social media, because they know the potential impact of their statements on capital markets.
The current and most visible example of this is Musk.
The SEC didn't comment.
The electric-car maker is awaiting a ruling on his role in the SolarCity acquisition, as well as his other legal troubles.
The lawsuit in San Francisco could be settled for between $260 million and $380 million, according to a report.
The price of settlement just went up, according to a professor at the University of Michigan Law School. It was a huge win for shareholders and an appeal of the decision by Musk might be hard to come by.
Nicholas Porritt, a lawyer representing shareholders, said he expects Chen's ruling to become public in the next few days.
Chen's decision means that Musk won't be able to argue to jurors that some of his statements were true, or that he didn't act fraudulently when he made them.
It has not been obtained in any similar case of this size.