The stock price of former President Donald J. Trump’s social media company has swung up and down over the past few weeks, but it may be in for an even wilder ride.

No stock is more directly linked to Tuesday’s election than Trump Media & Technology Group, the parent company of Truth Social. And the outcome of the race will have big ramifications for investors and for Mr. Trump, whose 57 percent stake in the company is currently valued at $3.9 billion.

If Mr. Trump is victorious, it could drive traffic and badly needed advertising dollars to Truth Social, which has become the former president’s main online megaphone for promoting himself and attacking his political foes. A victory by Mr. Trump could also provide a big jolt to shares of Trump Media and reward the more than 600,000 individual investors who make up its most loyal shareholders.

But if Vice President Kamala Harris wins, shares of the company that bear Mr. Trump’s name are likely to tumble. The future of Truth Social could be in jeopardy given that it has struggled to attract new users even during a heated presidential campaign and advertising revenues are coming in lower compared with a year ago.

“If you were going to get lots of subscribers it would seem this would be the time,” said Mike Stegemoller, a finance professor at Baylor University.