Polymarket: when some predict and others already know

Polymarket is often discussed as a way to find out what people really think about the future. Participants risk money, prices move with expectations, and the probability of an event appears right on the screen.

But stories increasingly emerge around the platform in which a participant’s advantage may have little to do with the quality of a prediction. Sometimes it involves access to data that has not been published yet. Sometimes it involves attempts to influence the source used to determine a bet’s outcome.

I have brought together several different cases. Their status matters: some involve formal charges, some reports of pressure, and others suspected interference under investigation.

Paris temperatures and the hair-dryer theory

In April 2026, bets on the highest temperature in Paris attracted attention. The relevant Polymarket markets were settled using readings from a weather station near Charles de Gaulle Airport.

On April 6 and 15, the sensor recorded unusual temperature spikes. According to Le Monde, the second episode happened in the evening, after dark. Participants who had backed a temperature scenario that looked unlikely before the spike won on the related markets.

Météo-France contacted the police over suspected interference with its equipment. Online, the story quickly became an account of someone betting on a high temperature, approaching the sensor and heating it with a hair dryer.

But there is an important distinction: the use of a hair dryer was not officially confirmed. It was one of the theories discussed to explain the anomalous readings. Neither the alleged offender’s identity nor a connection between a specific intervention and a specific bet can be considered established on the strength of this story alone.

Later, Polymarket’s Paris temperature markets switched to readings from the station at Le Bourget Airport. Euronews, Le Monde.

Google’s results before publication

Another case concerns Google’s annual Year in Search report. Polymarket offered contracts on which public figures would appear in the final search-trend rankings.

In May 2026, US authorities brought charges against Google employee Michele Spagnuolo. Prosecutors alleged that he used confidential company data before the publication of the 2025 report and made more than $1.2 million on related bets.

The outcome in this case depended on corporate data that ordinary market participants could not yet access. Formal charges, however, do not by themselves mean that guilt has been established in court. CFTC, Associated Press.

Bets on the operation against Maduro

In January 2026, a large win on contracts concerning events in Venezuela raised suspicions because of the timing of the trades. The story later developed beyond social-media discussion.

On April 23, the US Justice Department announced charges against soldier Gannon Ken Van Dyke. Investigators alleged that he participated in planning and carrying out the operation to capture Nicolás Maduro and used access to classified information to bet on Polymarket.

The prosecution alleges that he wagered around $33,000 on related outcomes and made approximately $410,000 in profit.

These are formal allegations about the use of confidential information, rather than facts established by a court judgment. DOJ.

Demands to change a journalist’s report

In March 2026, The Times of Israel’s military correspondent Emanuel Fabian reported pressure and threats after publishing a story about an Iranian missile strike.

According to the newspaper, people with an interest in a Polymarket outcome tried to force him to change his description of what happened. The report’s wording was central to a dispute over settling bets on an Iranian missile hitting Israeli territory.

The newspaper issued a public statement, and Polymarket condemned the threats. This case describes an attempt to influence the source confirming an event. It does not prove that the journalist changed his report or that the attempted manipulation succeeded. The Times of Israel.

A jump before the Nobel Prize announcement

In October 2025, shortly before the Nobel Peace Prize winner was announced, the market-implied probability of María Corina Machado winning rose sharply.

The movement attracted the Nobel Institute’s attention. Its director, Kristian Berg Harpviken, said a possible leak was being examined and called espionage the most likely explanation at that point, while stressing that what had happened was not yet established.

A price jump before an announcement does not by itself prove that a particular trader received confidential information. In this case, however, questions also came from the organisation responsible for keeping the decision secret until publication. VG.

Conclusions

These cases do not make every bet on Polymarket suspicious. But analysing public data, accessing confidential information and interfering with an outcome are not the same thing. In the first case, a prediction can be wrong. In the second, someone already knows what others are still trying to guess. In the third, someone tries to change the result itself or the source used to settle the bet.

So “the market got it right” tells me nothing about fairness. A public trading history does not reveal who is behind an account, what they knew or what they could influence either.

It is especially dangerous when bets create incentives to pressure journalists or tamper with equipment. The consequences extend beyond the platform and affect people who never participated in those bets.

Polymarket prohibits insider trading and manipulation. The question is not whether a ban exists, but how violations are detected and punished. Polymarket’s policy.

Insider information is possible in sports betting too: someone might know in advance that a key player will not be in the starting lineup or will miss a match through an injury that has not been announced yet. That does not guarantee a win, but it gives an advantage over people assessing the match using public information.

Before betting, I would look beyond the odds at settlement rules, source independence and the ability to challenge a result. An accurate market prediction does not mean equal conditions for its participants.