Kalshi has reportedly secured an exclusive prediction-market partnership with the US Open, expanding its sports footprint while legal disputes over event contracts intensify. Front Office Sports reported Sunday that the agreement takes effect immediately, citing two people familiar with the deal.

The agreement was finalized after qualifying ended last week, though financial terms and its full scope were not disclosed. The timing accelerates the USTA's earlier plan to consider prediction-market partnerships for 2027 and beyond. It also reflects how quickly sports properties have moved toward prediction-market sponsors after decades in which major leagues kept their distance from gambling-adjacent partnerships over integrity concerns; the NFL, NBA, MLB and others only began embracing legal sports betting sponsors after a 2018 Supreme Court ruling opened the door to state-regulated sports wagering.

Kalshi Secures Reported US Open Exclusivity Amid Legal Fight

New USTA CEO Craig Tiley reportedly played a central role in bringing the joint effort forward to 2026. Tiley began his tenure on July 20 after spending 21 years at Tennis Australia. The USTA hired him to expand tennis participation and strengthen the commercial reach of the US Open.

Under the reported agreement, rival prediction-market platforms would face advertising restrictions inside the venue and across television coverage. One source told Front Office Sports that competing platforms would be blocked from advertising at the tournament or on ESPN broadcasts.

That exclusivity could increase Kalshi's visibility during one of tennis's four Grand Slam events. ESPN holds exclusive US Open broadcast rights across ESPN, ESPN2, ESPN Deportes, ABC and its streaming platforms, with every match also available through the ESPN App. The broadcaster's 12-year agreement with the USTA keeps the tournament on ESPN through 2037.

However, neither Kalshi nor the USTA had publicly announced the deal by Sunday afternoon, and Kalshi was absent from the tournament's official partner list at that time. Earlier Sunday, the company published women's singles analysis with a disclaimer denying US Open or WTA affiliation.

The partnership follows a broader push by Kalshi into major American sports properties. On Aug. 25, it announced agreements with five Major League Baseball teams: the Atlanta Braves, Boston Red Sox, Los Angeles Dodgers, San Diego Padres and San Francisco Giants. Kalshi said baseball-related trading volume had risen 36-fold year over year.

The Dodgers and Red Sox separately described their deals as multi-year and exclusive. Their arrangements include branding, digital promotions and fan activations at two prominent baseball venues. Kalshi is not alone in courting sports audiences: rival platform Polymarket has pursued its own high-profile sports partnerships and marketing campaigns, intensifying competition for the advertising space that exclusive deals like the reported US Open arrangement would lock up.

Court Split Deepens as Kalshi Expands Across Major Sports

The expansion comes as courts remain divided over whether states may regulate sports event contracts offered on federally regulated prediction markets. KalshiEX operates as a CFTC-regulated designated contract market. The CFTC reaffirmed that status in a February enforcement advisory addressing misuse of nonpublic information on prediction markets.

Yet federal appellate courts have reached conflicting conclusions on state authority. In April, the Third Circuit ruled that New Jersey could not apply its gambling laws to Kalshi's federally regulated contracts. On Friday, the Ninth Circuit reached the opposite result involving Nevada, ruling that the state could enforce its gambling laws against the company. Reuters reported that the conflicting decisions could increase the likelihood of Supreme Court review.

That legal backdrop gives the reported US Open partnership added significance. The singles main draw began Aug. 30 and runs through Sept. 13 in New York. If formally confirmed, the agreement would place Kalshi before a major tennis audience while blocking direct prediction-market rivals from tournament advertising. Key open questions include whether the USTA and Kalshi publicly confirm the deal, whether other Grand Slams or major leagues follow with similar exclusive arrangements, and whether the circuit split ultimately reaches the Supreme Court — an outcome that could clarify the regulatory boundaries for prediction markets operating in sports.