A French weather agency has alerted police due to ‘interference’ with its sensors after several traders profited over $35,000 through precise timing on Paris temperature predictions. Météo France’s sensor near the Charles de Gaulle airport recorded unusual spikes of more than three degrees Celsius on April 6 and again on April 15. These anomalies were linked to significant trades in Polymarket markets, as reported by BFMTV and the Financial Times.
On April 6, one trader secured $14,000 from a market tied to this sensor with an initial investment of just a few dozen dollars, according to BFMTV. Blockchain analytics firm Bubblemaps noted another account on April 15 that bought ‘NO’ shares for an 18°C outcome when odds were below 1%. This trade involved roughly $120 and resulted in approximately $21,000, or a 180x return, within half an hour of the temperature spike.
“This particular bet is notable,” Bubblemaps remarked. “Typically, this trader’s average wager stands at $6 with 72% odds. Here, he placed a $120 bet on 0.6% odds, minutes prior to the anomaly.” Following these events, Météo France filed a complaint for ‘interference with an automated data processing system’ with the Roissy Air Transport Gendarmerie Brigade, citing physical inspections and sensor data analysis.
Mark Roulston of Lancaster University highlighted that prediction markets relying on single weather station readings are vulnerable. “Even without malicious intent, individual stations can produce faulty or odd readings,” he explained, advocating for contracts based on multiple stations to mitigate manipulation risks and enhance forecasting utility.
The trader’s account was reportedly created two days before the April 6 bet, raising suspicions about Polymarket’s potential role in market manipulation. This incident follows another integrity issue involving UFC announcer Bruce Buffer at UFC 327, where a live announcement error briefly inflated one fighter’s odds to 99.9%, leading to significant profits for a trader.
Amid growing scrutiny, platforms like Polymarket and Kalshi face legislative challenges, including a proposed U.S. bill by Senators Adam Schiff (D-CA) and John Curtis (R-UT) that would prohibit sports-related wagers on such platforms. Additionally, the Trump administration supports these platforms in legal battles against state regulations, asserting CFTC jurisdiction.
Polymarket is negotiating to raise $400 million at a valuation close to $15 billion, following a recent $600 million investment from Intercontinental Exchange.