Kalshi has locked in an unexpected last-minute arrangement that places the federally regulated prediction market platform in an exclusive official role at the 2026 US Open. The agreement with the United States Tennis Association took effect as the main draw opened at Flushing Meadows, even though organizers had previously signaled they would wait until 2027 or later before exploring such partnerships.
Two people familiar with the talks told Front Office Sports that the contract was not formally completed until after qualifying rounds wrapped last week.
Financial terms and many operational details remain undisclosed.
What is known is that the USTA is treating Kalshi as the sole prediction-market partner for the Grand Slam event this year.
A distinctive feature of the pact, according to one of those sources, is a restriction on rival platforms.
Other prediction-market operators are reportedly barred from advertising inside the tournament grounds and on television coverage, including ESPN broadcasts of the event.
That level of exclusivity is unusual for this category of sponsorship.
New USTA chief executive Craig Tiley is credited with accelerating the timeline.
Tiley, who previously spent more than a decade running Tennis Australia and the Australian Open, joined the USTA earlier in 2026 and assumed the CEO role in July.
Sources say he played a central part in moving the partnership forward for the current championships rather than postponing it.
The rollout itself has been quiet.
As play began Sunday, Kalshi did not yet appear on the US Open’s published list of official partners.
The company had posted a tournament preview earlier the same day that still carried a disclaimer stating it was not affiliated with the US Open or the WTA.
Kalshi declined to comment on the reported deal; USTA and ESPN representatives did not immediately respond.
The partnership fits a broader pattern of Kalshi’s expansion into sports.
The platform already holds official prediction-market relationships with the NHL (shared with another operator) and recently added multi-year team-level deals with five Major League Baseball clubs.
Event contracts on the US Open, including markets for men’s and women’s singles champions, were already live on the exchange before the partnership became public.
Trading volume on the women’s singles winner market had reached roughly $1.5 million by the early stages of the main draw.
Prediction markets differ from traditional sportsbooks.
Participants buy and sell contracts that pay out based on whether a stated outcome occurs, with prices reflecting the crowd’s implied probability.
Kalshi operates under Commodity Futures Trading Commission (CFTC) oversight rather than state gambling licenses, a distinction that has produced ongoing legal disputes in several jurisdictions.
The US Open arrangement gives the company a high-profile stage at one of tennis’s four majors while the regulatory picture continues to evolve.
For the USTA, the deal represents an early test of how prediction markets might sit alongside traditional sponsorships and broadcast partners.
Organizers had previously cited questions around match integrity among the reasons for a cautious approach.
Tiley’s willingness to proceed this year suggests those concerns were either addressed or judged manageable for a limited, exclusive arrangement.
Whether the partnership produces visible on-site branding, data integrations in coverage, or simply advertising exclusivity remains to be seen as the tournament unfolds. What is clear is that Kalshi now occupies the official prediction market slot at the 2026 US Open, a position that arrived later and more quietly than most sponsorships of this scale.