One afternoon last month, Chad Nedohin, a part-time pastor and die-hard supporter of Donald J. Trump, put on a pirate costume, set up his microphone and recited a prayer.

Mr. Nedohin was opening his latest livestream on the right-wing video site Rumble, where he has about 1,400 followers who share a devotion to Trump Media & Technology Group, the former president’s social media company.

“Faith comes from hearing — that is, hearing the good news about Christ,” said Mr. Nedohin, 40, his face framed by fake dreadlocks under a pirate-style hat.

Mr. Nedohin and his viewers were waiting for the results of a merger vote that would determine whether Mr. Trump’s company could start selling stock on Wall Street. Soon the news about Trump Media arrived via an audio feed: It was going public.

Mr. Nedohin raised his arms in celebration. A few minutes later, he cut to a video of a rocket blasting into the sky, with Mr. Trump photoshopped onto it. “We are holding Trump stocks,” he declared. “We are now financial investors in him.”

Mr. Nedohin is one of hundreds of thousands of amateur investors who own shares of Trump Media, convinced that its sole platform, Truth Social, will become one of the world’s most popular and profitable social media sites. In recent months, tens of thousands of Trump fans have tuned into Mr. Nedohin’s webcasts, where he exhorts viewers to invest in the company, arguing that “Trump always wins in the long run.”

The enthusiasm from Mr. Nedohin and other Trump supporters has turned Trump Media into the latest “meme stock,” driven more by internet hype than business fundamentals. In the public markets, these amateur investors have found themselves pitted against professional short sellers, specialist investors who bet that stocks will fail, as well as frantic day traders looking for a quick profit.

As a result, Trump Media’s stock price has swung wildly, sometimes dropping as much as 18 percent or rising as much as 28 percent in a single day. The company is “a meme stock on steroids,” one analyst recently wrote.

The stock’s unpredictable swings have major implications for Mr. Trump’s finances. The presumptive Republican presidential nominee owns more than $4 billion in Trump Media shares, including recently awarded bonus shares — a potential lifeline as he faces steep legal bills tied to the cases against him. The stock’s volatility could add hundreds of millions of dollars to his paper wealth — or vaporize it.

A Canadian citizen, Mr. Nedohin cannot vote for Mr. Trump in November. But he owns more than 1,000 shares in Trump Media, which are trading at about $36, down roughly 50 percent from its peak in March.

Mr. Nedohin began buying the shares in late 2021, after Digital World Acquisition Corporation, a publicly traded shell company, announced plans to merge with Trump Media. Digital World was trading at $93 a share at the time.

Once the merger was final on March 25, Trump Media began trading on Wall Street, and the original Digital World shares were converted into Trump Media stock under the ticker DJT.

Mr. Nedohin said he had held on to his shares and didn’t plan to sell. On the livestream, he interacts with viewers who use screen names like GOATPOTUS, urging them to keep the faith even when prices fall. “Don’t freak out,” he said on a recent show.

Truth Social “has the potential to easily eclipse Twitter,” the app now known as X, Mr. Nedohin said in an interview. “I’m not concerned about my investment whatsoever.”

Mr. Nedohin doesn’t like the term “meme stock” and prefers “populist retail investment.” But if he’s wrong about his bet, the financial impact on his viewers and Trump Media’s other investors could be devastating, given the risks of these volatile stocks.

By traditional metrics, Trump Media is not a successful business. The company reported $4 million in revenue last year and $58 million in losses. Compared with mainstream social sites, Truth Social has a minuscule audience — 1.5 million people visited the site last month, according to data from Similarweb, a small fraction of the 75 million who logged on to X.

Still, loyal investors like Mr. Nedohin are one reason Trump Media’s stock now trades at a valuation roughly equivalent to that of established companies like Wendy’s and Western Union. This month, Devin Nunes, Trump Media’s chief executive and a former Republican congressman, cited the enthusiasm of retail investors as a sign of the company’s strength.

Any suggestion that those traders might lose money amounts to “punching down at hundreds of thousands of everyday American retail investors,” Shannon Devine, a Trump Media spokeswoman, said in an email.

From his home in Edmonton, Alberta, Mr. Nedohin works as an engineer, calculating mechanical stress on pipes. But his passion is ministry: Although not ordained, he said, he has taken part-time gigs at local churches, leading worship groups as a nondenominational lay pastor. He’s also a guitarist, with a portfolio of original Christian songs, some of which have played on Canadian radio.

Before Truth Social, he said, he sometimes posted on Facebook but never got much traction. He craved an alternative.

In 2021, Mr. Trump co-founded Trump Media after he was kicked off Twitter for his incendiary posts before the U.S. Capitol riot on Jan. 6. A year later, Truth Social went live, managed by two former contestants on “The Apprentice.”

Mr. Nedohin had been a fan ever since Mr. Trump glided down the escalator at Trump Tower in Manhattan to announce his 2016 campaign. He considers the former president a supporter of Christian values, and believes the 2020 election was stolen from him.

Mr. Nedohin created a Truth Social account in May 2022 and soon found a community that shared his two main interests: Christianity and Digital World’s stock.

“I’ve never met such an amazing group of people who are so happy to have freedom of speech,” he said.

But Truth Social was glitchy, and Mr. Trump took months to post his first message. In 2022, the two “Apprentice” contestants left Trump Media after the Securities and Exchange Commission opened an investigation into the Digital World merger.

That inquiry delayed Trump Media’s plans to go public, and the price of Digital World’s stock dropped. Mr. Nedohin was concerned. But in the spring of 2022, he said, he received a message from God.

“You ask him to move a mountain, and sometimes he hands you a shovel,” Mr. Nedohin said. This time, he said, “that little voice inside” told him to start a podcast.

Mr. Nedohin started the Rumble show, “DWAC’d Live!” — a reference to Digital World’s stock symbol. On the show, he tried to mobilize Truth Social’s users, urging them to send letters to Congress protesting the S.E.C.’s investigation.

He adopted the pirate persona to drive attention, he said, calling himself “Captain DWAC” on the livestream. On Truth Social, he emerged as what passes for an influencer, with 6,600 followers.

Mr. Nedohin’s advocacy got the attention of Eric Swider, a Trump Media board member and former Digital World chief executive, who appeared on “DWAC’d Live!” last year.

“Make sure that you help get the word out there,” Mr. Swider said on the show, adding that “we’re very, very grateful for your assistance.”

In July, Digital World settled with the S.E.C. for $18 million, paving the way for the merger with Trump Media to be approved last month. Mr. Nedohin was ecstatic.

But the drop in Trump Media’s share price has caused consternation online, with some Truth Social users complaining that they have lost money. Much of the frustration has been directed at short sellers.

Trump Media posted instructions for shareholders on its website explaining how to prevent brokerage firms from lending shares to short sellers. Last week, Mr. Nunes wrote a letter to the Nasdaq, where the stock is listed, complaining about “potential market manipulation.” He followed that up with letters on Tuesday to the Republican chairs of several congressional committees. Mr. Trump previously warned that short sellers could “get hurt very badly.”

“As a Christian, I don’t believe in shorting,” Mr. Nedohin said. “I believe in only building for the positive.”

He remains fully committed to Truth Social. During the S.E.C. protest, he said, he returned to X, hoping to raise awareness about the campaign. Now that Trump Media is a public company, “I will never need to reach any of the people that are on there,” he said.

As his livestream ended, Mr. Nedohin deleted his X account.

Audio produced by Adrienne Hurst.