The recent price hike for lifesaving EpiPens is a nightmare for the people who need them and now can’t afford them. But one of Donald Trump’s top backers is hoping those EpiPens can become a financial bonanza. He’s bet hundreds of millions of dollars on the company that makes them.

As a result, he’s connected to a headline-nabbing controversy that involves a storied hedge fund, a powerful pharmaceutical company, and—naturally—both presidential candidates. As if 2016 wasn’t interesting enough.

John Paulson is a billionaire, and he manages the Paulson & Co. hedge fund. He’s a generous supporter of Republican politicians—he gave a cool $500,000 to the Republican Governor’s Association in 2014, for instance—and he’s one of the most powerful hedge fund guys to jump on the Trump Train. In June, he joined Trump at a $50,000-per-seat fundraiser at New York’s tony Le Cirque restaurant.

And a sizable chunk of Paulson’s cash is tied up in EpiPens. His hedge fund is a major investor in Mylan, the pharmaceutical company that manufactures them and raised their price by about 450 percent over the last 8 years, according to financial news site TheStreet. Paulson’s hedge fund owns 4.33 percent of Mylan’s shares, as Morningstar.com shows; only four entities own a greater percentage of the company’s shares.

As far as Paulson’s portfolio goes, Mylan is a very big deal. Seeking Alpha notes that those Mylan shares are his single largest holding, comprising 10.14 percent of his fund’s investments.

Paulson’s fund has been feeling a bit of pain lately. The investor may have become a Wall Street legend when he shorted the housing market before the collapse and made $15 billion for his hedge fund. That move has been called the greatest trade in history. But more recently, Paulson’s fund has fallen on comparatively hard times. Bloomberg reported on May 6 that its five biggest holdings lost him more than $2.3 billion in 2016.

That brings us to Mylan, which is the fund’s biggest holding. Paulson bought 7 million shares in the company in April of 2015, according to filings that FirstWord Pharma highlighted. That took his investment in the firm from 15 million shares to the 22 million shares he currently holds.

So far, it’s been a lousy bet. Mylan shares are down more than 40 percent since their April 2015 highs. And the company’s decision to dramatically ratchet up prices for EpiPens—lifesaving medication that parents of children with severe allergies have to buy every year—has, in the short run, only driven the company’s valuation further down. But in the long term, it could help offset some of the struggles Paulson’s firm has faced.

Some activists pushing for stricter regulations on Wall Street believe Paulson may be more than a passenger on Mylan’s wild stock market ride. They say hedge funds like Paulson’s sometimes pressure the companies in which they invest to take drastic measures to rapidly increase profits—or else.

“The activist investor class is very well known on Wall Street and is very well known among corporate executives,” said Mike Kink, the executive director of the labor-backed Strong Economy for All Coalition. “When your CFO walks into your office and tells you John Paulson has just taken a billion-dollar stake in your company, it’s like lighting a 400 degree fire under your desk chair. You know that there is someone looking over your shoulder.”

Sometimes, he said, this means pharmaceutical companies jack up drug prices to boost profits and please investors. Last year, his organization analyzed 25 recent and substantial drug-price hikes. Their conclusion: In 20 of those cases, hedge funds, private equity investors, or other wealthy speculators were involved.

“Out of the 25 drugs with the fastest-rising prices over the past two years, 20 are owned or have been acquired by firms with significant activity from hedge fund, private equity, or venture capital firms during the relevant time period,” they wrote.

Kink said investments from hedge funds like Paulson’s can make CEOs fear for their jobs—they sense that if their profits aren’t high enough, the fund will try to get them fired. Sometimes, fund managers write lengthy public letters berating CEOs for not making their companies sufficiently profitable. Other times, though, just increasing their holdings makes CEOs jittery.

“Merely by making the investment, you send a signal to the CEO that should spike their heart rate and start them scurrying towards a path towards short-term profits,” Kink said. “It is no secret what these guys do.”

A public relations representative for Paulson & Co. didn’t provide on-the-record comment for this story, and Mylan didn’t return multiple requests for comment.

Six years ago, Paulson’s fund reported a significant increase in its Mylan holdings. GuruFocus.com reported that he increased his investment in the firm by 163.85 percent, hitting 30 million shares on June 30, 2010. Since then, the cost of an EpiPen 2-pack has gone from about $100 to more than $600, as NBC News detailed. Prices vary depending on what kind of insurance purchasers have and where they get the EpiPens. Tracy Bush, whose son has severe allergies, told NBC that she paid $220.99 for an EpiPen in 2010, and that this year, the price before insurance for the device was $1,118.08. NBC noted that Mylan has also raised prices on a host of other medications.

The price hike has generated universally negative news coverage, along with scores of critical headlines. But TheStreet concluded that the headlines won’t hurt Mylan’s stock prices in the long run. They cited CitiGroup analysis that found pharmaceutical companies like Mylan can be risky bets, given “higher risk inherent in some of these companies to drug pricing headlines.” But TheStreet said that shouldn’t necessarily deter potential investors; the site rates Mylan stock as a “BUY”—thanks in part to its growing profit margins.

Paulson isn’t the only Trump-loving billionaire whose hedge fund has invested in companies that jack up the prices of lifesaving drugs. Robert Mercer, who is co-CEO of the Renaissance Technologies hedge fund, is a major Trump booster who has growing clout within the campaign. Last March, his fund bet on a biopharmaceutical company called Gilead Sciences, shelling out about $88 million to make the company 0.21 percent of its overall portfolio, according to filings that Market Realist highlighted. The fund bet bigger in the final quarter of 2015, as hedge fund site Insider Monkey noted, increasing its holdings in the company by a whopping 727 percent.

In a write-up on the hedge fund, Motley Fool noted that the profitability of Gilead’s two Hepatitis C drugs make it appealing for investors. Those drugs are very expensive—so pricey, in fact, that Hillary Clinton singled them out on the campaign trail as evidence of corporate greed.

“It is so expensive that a lot of Americans are being left out,” she said last week, as The Hill reported. “And you know what really is upsetting about this is that drug company sells that same drug all over the world at a much lower price to everybody else.”

More recently, Clinton ripped Mylan for its EpiPen pricing. In a statement, she called the pricing “outrageous” and called for the company to lower it. That statement didn’t note that Mylan is also a Clinton Foundation donor. The Trump camp, however, pointed that out to The Wall Street Journal and called for the foundation to return the contributions it received from the company, “if Hillary Clinton is as outraged as she claims.”

So Republicans aren’t the only ones wrapped up in the drug-pricing controversy. Heather Bresch, the CEO of Mylan, is the daughter of West Virginia Democratic Sen. Joe Manchin. She gave herself a raise after hiking the EpiPen prices, and a host of her dad’s colleagues have now called on her to explain herself. Price gouging, it seems, can be a bipartisan affair.