The US Open has unexpectedly secured an exclusive partnership with prediction-market platform Kalshi for the 2026 tournament. Initially, the U.S. Tennis Association (USTA), which owns the event, did not plan to finalize any prediction-market deals this year, only considering such partners for future seasons. The sudden agreement was largely influenced by new USTA CEO Craig Tiley, who joined earlier this year after leading Tennis Australia, and was finalized just after the qualifying rounds ended.

Kalshi now holds exclusive rights as the US Open’s prediction-market partner, with the USTA preventing any other prediction-market companies from advertising within the venue or on TV broadcasts, including on ESPN. Despite the exclusivity, Kalshi clarifies that it is not officially affiliated with the US Open or the WTA. On the Kalshi platform, wagering has reached around $1.5 million on the women’s singles winner, with Aryna Sabalenka favored ahead of Coco Gauff and Iga Świątek.

Despite this development, the USTA has not formally approved prediction markets as partners, and Kalshi does not yet appear among the US Open’s official sponsors listed on the tournament’s site. Notably, no traditional sportsbooks are listed as official partners either. Meanwhile, the ATP Tour, which governs men’s pro tennis independently, has weighed in on regulation for prediction markets, supporting stricter rules from the Commodity Futures Trading Commission, including restrictions on contracts involving injuries and officiating.

Kalshi’s partnership with the US Open is part of a broader surge in prediction-market deals across sports, with Kalshi and competitor Polymarket securing agreements in the NHL and MLB. However, major leagues like the NFL and NBA remain cautious, having not yet embraced such partnerships despite ongoing talks. The US Open deal signals growing mainstream interest in prediction markets, even as legal and regulatory questions persist.