Vitalik has answers for prediction markets after hairdryer weather manipulation drama

Ethereum co-founder Vitalik Buterin is back to suggesting ways for prediction markets to do better after news reports claimed that a Polymarket trader might have tampered with the temperature terminal that the odds prediction platform uses to settle weather markets for the whole of Paris on two separate occasions, on April 6 and 15. 

The latest intervention came after traders allegedly earned about $34,000 by making sure the weather market for Paris closed in their favor, literally taking matters into their own hands. 

Reports from French local media claim that the suspected trader took a hand dryer to the Météo France weather sensor at the Paris-Charles de Gaulle Airport (CDG), temporarily raising the temperature above 21°C, thereby manipulating the single source of information that Polymarket uses to settle its Paris weather market. 

Vitalik calls out centralization risk after Paris weather manipulation

Commenting on a post describing the Paris weather market manipulation, Vitalik said: “Between this and the Myrnohrad incident, it’s pretty clear that a median-of-3 independent sources (if not more) for anything like this should be basically mandatory.”

The Ethereum co-founder questioned the logic of settling markets with hundreds of millions of dollars at stake on information from a single source that could be easily corrupted. 

Vitalik recalled the “Myrnohrad incident” from November 2025, when a market based on the Ukraine-Russia war was settled by corrupted data allegedly put out by a rogue Institute for the Study of War (ISW). That market ended up putting winning bettors up by about 33,000% after the very unlikely scenario that Russian forces would take the city of Myrnohrad in eastern Ukraine was thought to have hit, albeit erroneously. 

The centralization risk that relying on a single source to settle markets adds another layer to the market manipulation issues that have become a recurrent theme in prediction markets. 

One aspect, insider trading, has been addressed by Polymarket in recent platform moves and disclosures, after deliberate attempts to avoid commenting on the issue at the peak of the feature-versus-bug debate. 

Unlike Polymarket, Météo France did not leave any room for ambiguity as French media reported that the firm has escalated the issue to the Roissy air transport gendarmerie brigade “for alteration of the operation of an automated data processing system.”

How does Vitalik want prediction markets to work?

Vitalik’s “mandatory” suggestion to improve the accuracy of markets to avoid future single-point failures is to settle markets based on a “median-of-3 independent sources (if not more).” 

In an earlier reaction to the hairdryer fiasco, Vitalik proposed that the real problem with prediction markets not serving a higher truth-seeking purpose is that “major prediction market platforms are not launching many conditional markets.”

As Vitalik sees it, conditional markets are the “most socially useful.”  

Conditional markets are a little more complex than the simple “Yes/No” options offered by platforms such as Polymarket and Kalshi. These markets consider the results of an earlier, related event to settle the current market. 

Vitalik credited these conditional markets for helping Democrats choose the better candidate in 2024 based on activity on Biden or Kamala winning the party’s nomination versus their odds of actually winning the presidential election. 

Vitalik is no stranger to the prediction market. Cryptopolitan reported earlier in the year that Buterin has made $70,000 wagering against “crazy mode” on Polymarket, hinting that he enters the market when bettors appear to have crossed common sense boundaries. 

The co-founder shared similar sentiments in December 2025, calling prediction markets truth-seeking environments, unlike social media platforms, where people can make sensational claims they don’t even believe in just to generate engagement. The financial stakes of these markets act as an accountability anchor because they now have real implications. 

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