An unidentified trader may have made $21,000 on a bet on abnormal weather in Paris

An unidentified trader could earn more than $21,000 at a time on cryptocurrency platform Polymarket by betting on abnormal warming in Paris, The Wall Street Journal reports.

Polymarket posts contracts every day that allow users to bid on maximum temperatures in dozens of cities around the world. Weather contracts for Paris are based on the readings of the weather station at Charles de Gaulle airport, which are published by the Weather Underground service.

According to blockchain analytics platform Bubblemaps, on April 15, a trader with the nickname xX25Xx bet just under $120 that Paris would be above 18°C that day. The bet had a low probability of winning: other traders were more than 99% sure that the temperature would not rise above that level, the WSJ reported.

In Paris on April 15, it was 18°C at its peak during the day and temperatures began to drop in the evening. However, at 21:30 local time - shortly after xX25Xx made his bid - the weather station at the airport recorded an unexplained short-term temperature spike to 22°C, the publication describes. Other weather stations nearby did not show a similar anomaly.

This is not the first strange jump in temperature at the weather station at the Paris airport. On the evening of April 6, it also recorded a sharp warming, WSJ writes. That day, a trader under the nickname Hoaqin made almost $14,000 on Polymarket by betting that the temperature in Paris would peak at 21°C, even though it was only hovering around 18°C in the afternoon.

Anomalies in the work of the weather station attracted the attention of amateur meteorologists on specialized forums, writes WSJ. Suspecting interference, they turned to the national service Météo-France. The latter, in turn, filed a complaint with the police about alleged interference in the automated data collection system.

Polymarket declined to comment. WSJ was unable to contact the traders. xX25Xx has already deleted his nickname on Polymarket and now appears as an anonymous account without proper labeling.

In the past, traders have reported attempts to manipulate betting outcomes on Polymarket by interfering with the data sources used to determine outcomes. For example, in March, an Israeli journalist reported receiving threats from traders demanding that his article on the Iranian missile attack on March 10 be corrected, which was the basis on which the bets were adjusted.

Shortly thereafter, Polymarket directly banned insider trading and market manipulation on its platform for the first time. According to the updated rules, users cannot trade contracts if they are able to influence the outcome of the underlying event.

This article was AI-translated and verified by a human editor