But experts say, this time, he may dodge any legal fallout.
On Tuesday (August 16) the billionaire tweeted that he planned to buy struggling English soccer club Manchester United.
He later said that was a "joke".
But the tweet briefly sent the club's U.S. shares soaring by as much as 17%.
Now lawyers say the Securities and Exchange Commission will want to know if Musk deliberately manipulated the stock.
The SEC already has several probes open into other tweets by Musk.
He paid a $20 million fine over one in 2018 that said he had funding to take Tesla private.
The watchdog concluded he really didn't.
But the bar for any new action looks high.
Musk isn't a Man Utd executive, and there's no indication he has any financial interest in it.
His colorful track record may also offer a strange kind of protection.
By now, lawyers say, investors ought to know that Musk just might be joking.
