Jeff Yass, the billionaire Wall Street financier and Republican megadonor who is a major investor in the parent company of TikTok, was also the biggest institutional shareholder of the shell company that recently merged with former President Donald J. Trump’s social media company.

A December regulatory filing showed that Mr. Yass’s trading firm, Susquehanna International Group, owned about 2 percent of Digital World Acquisition Corp., which merged with Trump Media & Technology Group on Friday. That stake, of about 605,000 shares, was worth about $22 million based on Digital World’s last closing share price.

It’s unclear if Susquehanna still owns those shares, because big investors disclose their holdings to regulators only periodically. But if it did retain its stake, Mr. Yass’s firm would become one of Trump Media’s larger institutional shareholders when it begins trading this week following the merger.

Shares of Digital World have surged about 140 percent this year as the merger with the parent company of Truth Social, Mr. Trump’s social media platform, drew closer and Mr. Trump became the presumptive Republican nominee for president.

“Susquehanna is a market maker and has zero economic interest in Trump Media,” said the company in a statement. “The firm’s long position is offset by short positions of the same size.”

Regulatory filings show the firm used offsetting securities to try to minimize its gains or losses in the stock.

The company statement did not comment on whether the firm still owned a stake in Digital World, or on the relationship between Mr. Yass and Mr. Trump.

Mr. Yass has been in the news recently for multiple reasons. A big contributor to Republican candidates and political action committees that support libertarian and conservative causes, including the Club for Growth, Mr. Yass’s firm is also a big shareholder in ByteDance, TikTok’s parent company. The U.S. investment firms Susquehanna, BlackRock and General Atlantic and others own 60 percent of ByteDance.

This month, the House passed a bill to force ByteDance to sell TikTok, the Chinese-controlled social media company.

The Club for Growth has sought to lobby Republicans in Congress to oppose any attempt to ban TikTok if it was still controlled by China, and Mr. Yass has helped the conservative organization fund that effort. (The Club for Growth had opposed Mr. Trump’s re-election campaign, but appears to have reconciled with him.)

Mr. Trump had supported banning TikTok in the United States, but he recently reversed his stance. A few weeks ago, he acknowledged having a brief meeting with Mr. Yass — identified in a 2022 Wall Street Journal column as a “never Trumper” — but said the two men never discussed TikTok.

A person close to Mr. Trump’s campaign said that Mr. Yass was expected to give a large donation to a group supporting the former president’s political campaign. Mr. Yass said through a spokesman that he had never given to Mr. Trump and had no plans to do so.

Susquehanna, which facilitates trades in thousands of stocks using mathematical models, isn’t the only firm that stands to make money on Digital World. In February, Digital World disclosed that it raised $50 million from a group of institutional investors to cover expenses related to the merger. The investors lent the company money that can be converted into shares. The investors in the deal have yet to be disclosed.

Overall, hedge funds and trading firms owned around 5 percent of Digital World’s 30 million shares outstanding at the end of last year. The vast majority of Digital World’s roughly 400,000 shareholders are individual investors, many of them supporters of Mr. Trump.

The surge in the price of Digital World shares this year has boosted the value of Mr. Trump’s 79-million-share stake in Trump Media by billions of dollars. Mr. Trump is also being issued a class of shares that will give him at least 55 percent voting power over all shareholder measures.

The merger was finalized just before Mr. Trump’s Monday deadline to secure a bond to cover a $454 million penalty imposed by a judge in a civil fraud case.

The former president’s Trump Media shares could provide him with a financial lifeline to raise the cash needed to get a bond. But to do that, he needs Trump Media’s seven-member board to remove a restriction that prevents him from selling shares or using shares as collateral for a bond for the next six months.

The board includes Mr. Trump’s eldest son, Donald Jr., and three former members of his administration: Kash Patel, who was the chief of staff to Mr. Trump’s acting secretary of defense; the former U.S. trade representative Robert Lighthizer; and Linda McMahon, a former administrator of the Small Business Administration.

Ms. McMahon is a chair of a big fund-raiser for Mr. Trump scheduled for April 6 in Palm Beach, Fla., according to a copy of the invitation. The event is co-hosted by John Paulson, the billionaire investor, and includes a number of Wall Street financiers as chairs. Mr. Yass is not mentioned as one of them.

Maggie Haberman contributed reporting.