Elon Musk’s Twitter deal includes a $ 1 billion breakup fee.

If the $ 44 billion deal between Elon Musk and Twitter if separated, both sides may have to pay the other billion dollars, according to a securities filing on Tuesday.

The richest man in the world struck a deal Monday to buy the social media company for $ 54.20 per share. Mr. Musk, who also heads electric carmaker Tesla and rocket maker SpaceX, said he intends to make Twitter private and that he wants to improve the product and promote free speech on the platform.

The deal won’t end for another three to six months, Twitter told its employees on Monday. According to Tuesday’s filing, Twitter is expected to pay Mr. Musk under certain circumstances if the deal goes wrong. This would include if the social media company signed a deal with another suitor whose offer it deemed superior. Mr. Musk, on his part, would have to pay if his deal funding falls apart.

Twitter declined to comment. Mr. Musk did not immediately respond to a request for comment.

Mr. Musk’s funding played a key role in the intrigue of the deal. Initially he didn’t seem to have any funding online for him to offer him. But last week he revealed in a filing that he has loan commitments from various banks. Mr. Musk is paying with 13 billion dollars in bank loans, plus another 12.5 billion dollars in loans against his shares in Tesla. He promised another 21 billion dollars in cash, even if he didn’t delineate the source of that money.

Asking a buyer to accept a commission if the funding falls apart isn’t atypical, lawyers said. The commission that Mr. Musk is hooked on – about 2.5 percent of the deal – is on par with other acquisitions.

“It’s actually a pretty straightforward merger agreement,” said Steven Davidoff Solomon, a professor in the School of Law at the University of California, Berkeley.

The filing also stated that if a deal is not concluded by October. 24, both sides may leave. If the transaction was still pending regulatory approval at the time, Musk and Twitter would have another six months to close it.

US regulators may look into Musk’s purchase of Twitter, but they are unlikely to sue to block itsince it’s not an example of a company buying a competitor, former antitrust officials said.

European officials said Tuesday that Twitter under the ownership of Mr. Musk should have respected his new Digital Services Act. The historic law, likely to go into effect within the next year, requires social media companies to monitor their platforms more aggressively to combat disinformation and restrict certain online ads.

Mike Isacco contributed reportage.