The SEC and Tesla did not immediately respond to requests for comment.
The tweet ends with "the name change is so on point", which appears to be a reference to the SEC - mocking the agency. (FOX), to replace Elon Musk as the company's chairman, people familiar with the matter told The New York Times.
The SEC declined to comment on the tweet.
Under the deal reached between the SEC and Mr Musk last weekend, Mr Musk will remain as Tesla CEO but has to step down as chairman for three years.
Tesla stock dropped 2 percent in after-hours trading after Thursday's tweet. Musk wrote on Twitter in an apparent jab at the SEC and short sellers, who he has slammed on social media before.
Thomas Gorman, a partner at Dorsey & Whitney in Washington, D.C., said Musk might argue that the latest tweet might be a mere "personal lament", and not a violation of the settlement.
While Musk wanted to fight the SEC, he reportedly had a change of heart when Tesla's stock plummeted almost 14 percent after the lawsuit was announced.
Musk is a long time critic of what he believes is a bias towards Short Sellers (ask an accountant).
Nevertheless, Musk doubled down on Thursday after getting questioned by another Twitter user about the tweet.
"I think it is juvenile and sophomoric and narcissistic, but I don't think it has particular relevance to the subject of the lawsuit against him", said Harvey Pitt, the SEC chairman under President George W. Bush.
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Richard Blumenthal of CT , who sits on the Judiciary Committee and is a frequent Trump critic, slammed Trump for the remark. You know, here's what's personally degrading: "This is what you get when you go through a trailer park with a $100 bill".
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Major League Baseball has said it began an investigation a year ago after allegations first became public. Russell will not appeal the suspension, per the announcement.