Trump Media shares rose Monday, two days after former President Donald Trump returned to Butler, Pennsylvania, the site of the July 13 assassination attempt, for a campaign rally accompanied by Tesla CEO Elon Musk.

Shares closed up 11.45% at $18.39 a share after a heavy trading day. As of Monday's close, the media company had a market cap of about $3.681 billion.

In Butler, Musk took the stage in the middle of Trump's 90-minute speech to praise the Republican presidential nominee and describe himself as not just MAGA but Dark MAGA.

“This is not a normal election,” Musk said. “President Trump must win to preserve the Constitution. He must win to preserve democracy in America.”

The billionaire businessman first publicly endorsed Trump for president in the hours after the failed assassination attempt on July 13. Musk has since become a major backer of Trump's campaign against his opponent Kamala Harris.

In further support, billionaire Elon Musk also created a pro-Trump political action committee, America PAC, which came under investigation earlier this year after complaints about voter data. The investigation has since been closed with no further action taken against the PAC.

Trump, in turn, said he would create a government efficiency commission proposed by Musk if elected president, to audit and cut waste across the federal government. Trump also suggested appointing Musk to lead the commission.

In previous regulatory filings, Trump Media has said the success of its flagship product, Truth Social, depends on Trump’s popularity and continued use of the platform. Trump owns about 57% of the company’s stock.

Trump Media shares have fallen 54.68% since their high in July after the first assassination attempt on Trump. The shares hit a new 52-week low on Sept. 23 and have since recovered modestly, despite recent reports of turmoil within the company.

Trump Media revealed in a regulatory filing Thursday that Chief Operating Officer Andrew Northwall resigned in late September.

In the same filing, the company announced that it would release nearly 800,000 shares of its stock to an early investor at the order of a Delaware judge, who found that Trump Media had violated an agreement with that investor.