A betting market that is being touted by Donald Trump’s supporters as proof that he will win the election has been manipulated by multi-million dollar wagers to make him appear certain of victory, experts are warning.

Polymarket has become a viral phenomenon for showing high “percentage chances” of Trump winning, leading to it being widely quoted on X and elsewhere to show that a race that polls suggest is deadlocked is in fact extremely likely to go his way.

At the time of writing, Polymarket says Trump has a 61.9 percent chance of beating Vice President Kamala Harris.

Among those talking it up is Elon Musk, who has claimed the online market is more accurate than political polls, and boosted it on his X account. Another is Joe Kernen, the conservative-leaning CNBC Squawk Box co-host, who has repeatedly referenced it on air and on X.

The site is funded by the GOP mega-donor Peter Thiel, a close friend of Musk.

A whopping $30 million—enough to significantly increase the likelihood Polymarket tells its users Trump has of winning—has been pumped into Polymarket this fall from a quartet of accounts. Experts believe they may be controlled by the same person, The Wall Street Journal reported.

Polymarket works by letting people use crypto currencies to bet anonymously on world events. Like any conventional betting system, the more money goes into one outcome, the higher the percentage the site will predict of that outcome happening—meaning that putting huge amounts of money into gambling on a Trump victory will push up the site’s percentage chance of a Republican win on election day.

The multi-million dollar wagers identified by The Wall Street Journal—placed by the users Fredi9999, Theo4, PrincessCaro, and Michie—were reportedly all in favor of a Trump win on Election Day, or iterations of it, like Trump winning Pennsylvania or the popular vote. Funds for the wagers were reportedly placed using Kraken, a U.S.-based crypto exchange.

The wagers appear to have drastically moved Polymarket’s general election odds in Trump’s favor. Kamala Harris had a 52.3 percent chance of winning the election a month ago, but was given just a 38.2 percent chance of winning on Friday morning.

Christopher Gerlacher, a political analyst for Prediction News who studies market trends, told the Daily Beast that “Polymarket’s spike was almost certainly a case of market manipulation.” He added that one of the mystery user’s accounts, Fredi9999, has more than twice as much money on Trump as the next highest gambler.

As Gerlacher notes, Polymarket’s odds shift doesn’t align with most political polls, which still show Trump, 78, and Harris, who turns 60 on Sunday, still neck-and-neck.

Yet, conservatives have latched onto the new Polymarket odds as supposed proof that Trump is pulling away and that pollsters are, like many were in 2016, again wrong about Trump’s true popularity. Gerlacher said it’s important that people realize that market odds—while sometimes in close alignment with polls—are still separate from polls, as was recently explained by the industry substack Manifold Markets.

“This shared misunderstanding has been reflected by many on Twitter who seem to believe a 20-point lead in a prediction market is equivalent to a 20-point lead in a poll,” the substack wrote on Thursday. “If a trustworthy poll suggested a 20-point lead then you’d be looking at something closer to a 90% chance of winning.”

Simon Rosenberg, a Democratic political strategist and blogger, has referred to the mass sharing of betting market movement by Republicans as “Polymarket voodoo,” which he’s described as useless when analyzing the state of the presidential election.

“Of course [Polymarket] could be manipulated by wealthy people from Russia, and China, and Iran, and Syria, wherever else, right?” Rosenberg said in an appearance on MeidasTouch. “You know, North Korea could be buying up and pushing the markets and the idea that we’re supposed to take all of that seriously—and this has some kind of relevance to our election—it’s so bonkers.”

Musk is all in on the so-called voodoo. He was among the first prominent Republicans to address Polymarket’s odds shift in Trump’s favor, and has since boosted it further.

“Trump now leading Kamala by 3% in betting markets,” he wrote on Oct. 6. “More accurate than polls, as actual money is on the line.”

A day later, Musk engaged with a post that included a screenshot of a Polymarket graph that showed Trump’s victory odds climbing. “Victory is not enough, it must be absolutely decisive victory,” he wrote.

It’s not just Musk who has pushed Polymarket as a legitimate barometer on the state of the presidential race. CNB’s Kernen also shared a screenshot of Trump’s Polymarket lead to attack another X user, Democratic commentator Fred Wellman, for claiming that Trump’s campaign was faltering.

Some fear the $30 million in Polymarket wagers could be a form of “market manipulation” and that Trump, should he lose on Nov. 5, might point to his vast Polymarket lead as proof the election was stolen from him.

However, the motive of the person or people behind these specific wagers, like their identity, remains a mystery. Prominent political gamblers have apparently tried to make contact with the mystery millionaire (or potentially billionaire) to learn more about them, but have been left with more questions than answers. The Journal reported that the oldest of the accounts was created in June, while the newest was created this month.

Harry Crane, a professor of statistics at Rutgers University, noted to the Journal that the user might not have nefarious reasons for making the wager. He indicated they may just have millions to blow and are confident in a Trump victory.

“Purchasing a large number of shares on one outcome does not require any ulterior motive or effort to manipulate the market,” he said.

After all, other betting markets—like Betfair in Britain and the New Zealand-based PredictIt—also favor a Trump victory on Election Day, though not quite to the degree of Polymarket.

Still, the Journal reports a source saying that Polymarket is “investigating the activity in its presidential-election markets with the assistance of outside experts.” This sort of investigation may become more common, as Gerlacher says political gambling markets have grown exponentially since the 2012 election.

Rajiv Sethi, a Barnard College professor who once wrote a paper about the practice of flooding markets to garner momentum for a candidate, told the Journal that he thinks Polymarket’s mystery gambler may be trying to give Trump a last-minute momentum boost.