Shares of former President Donald J. Trump’s social media company have been on a wild ride since making their debut on Wall Street in March: soaring, crashing and then climbing again.

The rally has pushed the value of Mr. Trump’s majority stake in the company to some $6 billion, a major windfall as he ramps up his presidential campaign and faces steep legal bills tied to the multiple cases against him.

On Wednesday, the share price of Trump Media & Technology Group traded around $52, approaching where the parent company of Truth Social ended its first day of trading on March 26, at just under $58.

Mr. Trump owns nearly two-thirds of the company, but he is not allowed to sell his shares or use them as collateral for a few months. Trump Media’s multibillion-dollar market valuation has put it in the same league as established companies like American Airlines and Hasbro.

The frenzied trading in Trump Media has been reminiscent of the mania around so-called meme stocks — shares that trade based on investor sentiment and momentum more than traditional financial fundamentals.

The company last year lost $58 million and took in just $4 million in revenue, all of it from advertising on Truth Social.

“A meme stock has no economic rationale,” said Mike Stegemoller, a finance professor at Baylor University. “It is like someone acting erratically on the street — just get out the way.”

In classic meme-stock fashion, there have been no major developments at Trump Media to propel the shares higher of late. But the stock trades in relation to how investors view Mr. Trump’s prospects in the upcoming presidential election, their fealty to the former president, and simply momentum and emotion.

The recent rise in Trump Media’s share price has also provided a sharp contrast to the scenes in a New York courtroom, where Mr. Trump is on trial for his role in a scheme to conceal hush-money payments to Stormy Daniels, an adult film star, in the final days of the 2016 presidential campaign.

Trump Media merged with a public shell company for its market listing, and more than 400,000 of the shareholders of that company are individual investors. Many of them are fans of Mr. Trump and users of Truth Social.

Digital World Acquisition Corporation, the shell company, began the year trading around $17.50 a share. That means it has been a banner year for early investors in Digital World who are now shareholders of Trump Media.

Michael Melkersen, a lawyer who lives in Puerto Rico, invested in Digital World before its initial public offering in 2021 and now has hundreds of thousands of shares of Trump Media. He said he had taken a gamble that paid off and was now looking to sell some shares.

“I believed in it,” he said, “but I am too heavily invested for my own comfort.”

Recent regulatory filings show that just a handful of investment advisory firms, which manage money for wealthy investors, held a meaningful amount of Trump Media shares at the end of March.

Sapient Capital, which manages $9 billion in assets for wealthy people and foundations, reported holding about 145,000 shares of Trump Media. A founding partner at the Indianpolis-based firm is a brother of Mike Pence, who served as vice president for Mr. Trump. The former vice president said in March that he would not endorse Mr. Trump this year. A Sapient spokesman said the shares were purchased at the request of its clients.

The filings also show that a few investment firms had significant positions in Trump Media warrants — a type of security that can be converted into shares in the future. The firms included Selway Asset Management, Magnus Financial Group and Nine Masts Capital, according to the regulatory tracking service Whalewisdom.

Justin Yochum, a co-owner of Selway, an Idaho-based investment advisory firm, said the firm had bought the warrants as part of a complex trading strategy to profit on the price difference between Trump Media’s shares and its warrants.

“I believe the company itself is worth zero,” Mr. Yochum said.

A few hedge funds reported holding “put” options on the stock. These allow investors to sell shares at a future date at a specified price, and are often bought by traders who think the price of a stock will fall.

Trump Media has been pushing back against short-sellers, as investors who bet on a stock’s fall are known, sending letters to stock exchanges and lawmakers asking for investigations into what it describes as “manipulation.”

S3 Partners, a market research firm, estimates that short sellers have incurred losses of $216 million on paper this year by betting against Trump Media.

As it happens, short-sellers have also recently been squeezed by a resurgence of GameStop, the original meme stock. Those losses were even greater, at more than $800 million, according to S3.

The stock roared back to life this week after the apparent return to social media of Keith Gill, a former broker who goes by the moniker “Roaring Kitty,” after a three-year hiatus. Mr. Gill was at the center of the initial meme-stock mania in 2021, when he encouraged investors to buy shares of GameStop, which he argued was undervalued.

GameStop’s stock has roughly doubled since Monday, on little news other than a series of cryptic posts on Mr. Gill’s X account.