There are worse things you could do than drive to a Parisian airport and mess with the airport thermometer—just for a few minutes! But why do it all the time?
To make money, maybe. This is the program that some strange person (or people) was reported in April to win bets on the market prediction platform Polymarket, which allows people to bet on the highest temperature in Paris on any given day, unlike weather derivatives. A popular version of the story says that the shadowy figure activated the sensor and the hair dryer—the photo showing this turned out to be AI generated—but it could be anything. Lightweight, hand warm.
By adding that number to the sensor, this person won about $20,000. The French police are investigating because you cannot cross the airport or destroy its equipment, but Polymarket did not return the victory. (It did changes the airport that it relies on for Paris temperature readings; the French government, however, access is blocked on stage this week.)
Over the past few years, much concern has been expressed about how prediction markets can enable—and create incentives for—local business. Some of the many people who have played the markets corresponding to when the war would begin, when the regime will changeor even whoever was at Taylor Swift’s wedding might have known the outcome before it happened. “Name markets,” which allow participants to bet on what words a public figure might use in a speech, or how long the speech will be, can of course be played by people close to the relevant figures—just last week, ABC News reported that the operator of the teleprompter in the White House has made more than 100,000 dollars by using Kalshi to promote the speeches of President Trump. (“The White House has strict ethical guidelines that we expect all staff and officials to follow,” a White House spokesman told the station, confirming that the staffer had been placed on leave.)
The issues with insider trading are clear: It’s illegal, for starters, and the platforms ban it, anyway. (Although insider trading also arguably serves the purpose of prediction markets, which is to channel the “wisdom of the crowd” into predicting an event that is highly likely to occur.) People can also easily identify and avoid markets that are more susceptible to it. But what about the hair dryer type of business, when an apparent outsider changes the course of events to make money for a certain outcome? “I think it’s probably a bigger issue or problem than local business,” Vincent Grégoire, professor of finance at HEC Montréal, told me. The Paris airport incident didn’t hurt anyone, but the future might. (You can think of a bunch of ways that someone could create a dangerous situation when, for example, trying delay the flight.)
Some experts call this type of deception “deception of the physical world”– confusion over market manipulation. I asked others for more interesting ideas. Joshua Mitts, a professor at Columbia Law School, wasn’t so sure manipulation it was the right word, because it has a specific definition for the financial markets, but he still continued to say it unfortunately as we talked. I agree that the word is missing a bit. Controlling the physical world is what I do every minute of every day when I breathe and walk. I would call this type of deception “foreign trade.”
Foreign trading is also against the rules of the forum. Both Polymarket and Kalshi prohibit any form of market manipulation. When I reached out to Polymarket to ask about what happened in Paris, a spokesperson sent me a statement from Olivia Chalos, its deputy chief legal officer, who wrote that Polymarket “maintains monitoring, auditing, enforcement, and reporting processes to address potential violations.”
But it is clearly a bit of a whack-a-mole situation. The US Commodity Futures Trading Commission recently proposed more federal rules for market prediction platforms to reduce the problem. One of the main recommendations was to prevent the listing of markets that would “create perverse financial incentives” – for example, markets on wildfires or market on as the famous monkey named Little Joe would escape from the zoo (for the second time). Polymarket includes a letter to the market explaining what laws a person would be breaking if they tried to free the chimpanzees themselves, and that they could face life imprisonment for doing so. That may be the first time a market prediction platform has featured such a warning, the Bloomberg writer Matt Levine noted in May journal“but I haven’t made a thorough investigation and I doubt it will be the last.”
The experts I spoke to said that the most attractive markets for this kind of manipulation would be based on a single number or a simple, specific outcome that the average person could cheaply influence—for example, the temperature in Paris. Caleb Davies, a popular internet market forecaster, highlighted another when he wrote about his experience losing thousands of dollars betting on Spotify’s streaming charts, something scammers had figured out how to game. juicing fake juice how many times a particular song was played. Davies says the experience led him to an epiphany. He doesn’t just play data on data, he said: “I also bet that no one will mix it up.” And that’s a bad bet.
Davies posted a screenshot to X showing that he has withdrawn about $250,000 from his Kalshi account, and says he has stopped using it entirely. “I love prediction markets,” he told me. “I’d love to keep playing in them. But right now, both platforms are trash, I think.” When contacted by the company for comment, Kalshi spokeswoman Jacki McGavick said that Kalshi “takes market manipulation or fraudulent activity as seriously as any government-regulated financial exchange” and is investigating the Spotify incident.
For the conversation, Davies went through Kalshi while we were on the phone, looking for opportunities to cheat. The Spotify charts were good, he knew. Rotten Tomatoes scores would be better (more money), though more difficult to play. (However, New York Matt Stieb of the newspaper think outside how to do it.) I told him that the market was open for preparing the first case of worms this year in the United States. You may expose yourself to some infected livestock. But he was not interested. “I think I’d rather not make money than do that,” he said. “I’ve read about it—it doesn’t look very interesting.”
Right now, platforms—which are very much in the form of advertising—carry a lot of markets that don’t have a ton of business. They want what they can to attract new users and earn revenue. Also, most of them are funny: Most people probably realize it’s a waste of money to bet on Little Joe the gorilla escaping, but it’s fun to talk about. As more forex trading stories emerge, though, people will be more reluctant to participate in markets that seem easy to steal. This problem, even more than the local business, may begin to limit what Polymarket and Kalshi can offer.
There are many things that platforms can do to intervene in foreign trade, Joshua Della Vedova, an assistant professor of finance at the University of San Diego’s business school, told me. They can control the size of bets in markets whose results would be easy to steal. They can look for suspicious businesses using some of the same methods that detect insider trading. His preferred approach seeks “excessive precision.” If someone bets that Olivia Rodrigo’s song will hit No. 1, that’s understandable—but if they’re also betting “no” on Drake and Charli XCX and Bad Bunny, then they’re showing a questionable level of confidence. That confidence can come from having an inside line, or it can come from using bots to increase streams illegally. Platforms may also not allow markets that are settled by looking at a single number from a single source, he suggested. That would solve the issue at the Paris airport, for example, and it’s not as if Polymarket wouldn’t use an aggregate of weather data, instead of just a single reading.
Without some change, platforms can continue to send signals through the real world—beyond the negative markets they choose to list. A The Wall Street Journal report found that Polymarket had been encouraging people to share videos and fake versions of their Polymarket dashboards, showing fake earnings on imaginary bets that never happened. The strangest to me were organized viral clips where Polymarket and Kalshi propelled the New York Knicks to their first NBA Championship in over 50 years.
In one of the clips, an alleged Knicks fan outside Madison Square Garden shouted, apparently in personification, “My Muslim mayor, my Jewish bags, my Christian Dior, Knicks in four.” Later, it turned out that he hadn’t made this up at all—someone had posted it as a TikTok comment weeks ago and parts of the song they were bigger—and that the microphone he shouted into was Kalshi-branded, the whole thing was a Kalshi wonder, no one seemed to care. The song turned out to be true. It was everywhere.
Platforms position themselves as virtual reality machines, which can mean a number of different things. Do they get it or do they do it? Sometimes, it can be difficult to distinguish between reflecting our reality and creating a new one—or doing both.
