When someone helpfully suggested a social media team could help him avoid typos and enraging the "Shortseller Enrichment Committee" [sic], Musk apologized for the typos - but not for slamming the SEC.
Musk used his Twitter account to jab the Securities and Exchange Commission, the same agency that went after him for an August 7 tweet in which he declared he had secured financing for a Tesla buyout. "And the name change is so on point!"
The Tesla boss agreed to pay a fine of $20m (£15m) to the Securities and Exchange Commission regarding a tweet he had written boasting that he had funding to take his firm private. It is also unclear whether this money will be used to cover Musk's $20 million SEC fine.
The stock dropped as much as 3.8 per cent as of 9:40 a.m. Friday in NY, after Musk fired off more than a dozen tweets targeting the Securities and Exchange Commission and short sellers the night before.
"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. "There's no real upside".
Musk has long feuded with short sellers, a category of investors that have been betting on Tesla's stock to fall.
But Musk and Tesla might not even be out of the woods yet.
Nathan said it was her regular practice to request such letters.More news: Ruby Rose named most 'dangerous' celeb
Nathan "may want to know why Tesla is paying a fine because the CEO doesn't know when to shut up", said Adam Pritchard, a University of MI law professor and former SEC lawyer.
Some Twitter users celebrated Musk's tweet, while others expressed disapproval.
Think you might need to download Grammarly for the future there Elon...
"Elon appears to be resistant to signing this agreement" said Gene Munster, a managing partner at venture capital firm Loup Ventures. "It's what they do", he tweeted. "Index managers like Blackrock pocket [sic] make excessive profit from short lending while pretending to charge low rates for "passive" index tracking".
The SEC declined to comment on the tweet.
A Tesla showroom is seen in Santa Monica, California, U.S., January 4, 2018.
The SEC had sought to remove Mr Musk from...
For her part, Nathan may have limited room to intervene, after a federal appeals court curbed the ability of judges to reject SEC settlements. "It's what they do", he said of the SEC.
Musk doubled down on the tweet shortly after.