Kalshi has entered a multi-year partnership with the United States Tennis Association (USTA) to become the Official Prediction Market Partner of the US Open. The agreement begins with the 2026 US Open Singles Main Draw and gives the prediction market operator visibility across the tournament’s digital platforms and through on-court signage.

The deal places Kalshi at one of tennis’s biggest events as trading activity around the sport continues to expand. The company said tennis-related trading volume on its platform has increased 25-fold year over year, while its overall user base has reached millions.

The partnership also includes measures intended to address integrity concerns linked to prediction markets. The USTA and Kalshi have agreed to restrict markets involving areas such as umpire decisions and code violations, where trading could create concerns around competitive fairness.

Kalshi has separately entered into a confidential data-sharing agreement with the International Tennis Integrity Agency (ITIA). The arrangement will support real-time market surveillance during the US Open and forms part of the broader integrity framework established for the tournament.

USTA CEO Craig Tiley said: “We’re relentless about keeping tennis at the cutting edge of global sports innovation and fan connection. Partnering with Kalshi gives us an opportunity to pioneer that next generation of fan engagement while ensuring the integrity of our sport.”

The tournament’s main draw began in New York on August 31 and runs through September 13. The US Open is described in the supplied material as the largest tennis event in the world, with 1.14 million fans and a prize pool exceeding $100 million.

Prediction Markets Gain Ground in Tennis

The agreement follows a period of increased activity by Kalshi in tennis. Earlier in August, the company reached a deal with Catalist Sports that provides access to livestreams and data covering more than 65,000 tennis matches.

Kalshi co-founder and CEO Tarek Mansour said in a press release: “Every summer the US Open takes over New York, and as a New York company, we’re proud to be part of it. Tennis is one of the fastest-growing sports on Kalshi, with fans using our markets to understand what’s happening throughout the tournament. We’re proud to partner with the USTA to give fans even more ways to engage with the game they love.”

Prediction markets allow users to trade contracts linked to outcomes. The material provided describes tennis markets covering match winners, set outcomes and tournament futures, with positions available during live competition.

Kalshi expanded into sports event contracts across leagues including the NFL, NBA and MLB in early 2025. Sports have since become a major part of its activity, accounting for a reported 80% of its trading volume.

The company has also pursued agreements across other major sports properties. Its recent deals include multi-year marketing partnerships with the Atlanta Braves, Boston Red Sox, Los Angeles Dodgers, San Diego Padres and San Francisco Giants. Kalshi also has partnerships involving the NHL and Chicago Blackhawks, alongside agreements with soccer leagues.

The platform has recorded more than $178 billion in trading volume since launching before the 2024 presidential election as a political and financial trading exchange.

US Open Deal Includes Integrity Controls

The USTA and Kalshi have incorporated specific restrictions into their agreement rather than treating the partnership solely as a commercial arrangement. Markets involving umpire rulings and code violations will be restricted because of their potential integrity implications.

The ITIA data-sharing agreement will add another layer of monitoring during the tournament. The information provided to the market operator under that arrangement will support real-time surveillance.

The USTA said the integrity framework also includes proactive monitoring, stakeholder education and compliance enforcement. These measures accompany the restrictions on particular event contracts as prediction markets gain greater exposure within professional sports.

The partnership therefore gives Kalshi a prominent presence at the US Open while establishing boundaries around the types of tennis-related markets available during the tournament.