US Open Signs Exclusive Prediction Market Deal with Kalshi - First for a Tennis Major

The US Open, one of tennis's four Grand Slam tournaments, has brought prediction market platform Kalshi on board as an official partner. This marks the first time a prediction market operator has signed an exclusive deal with a tennis major.

According to Front Office Sports (FOS) on the 30th (local time), Kalshi has entered into an exclusive prediction market platform partnership agreement with the United States Tennis Association (USTA) for the US Open. The deal took effect immediately and was reportedly finalized after the qualifying rounds concluded last week. Specific financial terms and conditions were not disclosed.

The USTA had originally planned to consider partnerships with prediction market firms no earlier than 2027. Concerns about match integrity were also reportedly raised during discussions. However, Craig Tiley, who took over as USTA CEO in July, is said to have played a leading role in launching the collaboration starting with this year's tournament.

Exclusivity is the centerpiece of the agreement. According to FOS, the USTA intends to restrict other prediction market platforms from advertising not only at US Open venues but also during ESPN's tournament broadcasts. The contract reportedly includes provisions granting Kalshi exclusive advertising rights.

The deal moved so quickly that traces of the previous status quo lingered even after the main draw began. As of Sunday afternoon, Kalshi was still absent from the tournament's official partner list, and Kalshi's articles related to the women's singles still carried a disclaimer stating the company was "not affiliated with the US Open or the WTA."

Nevertheless, trading is already active. By early Monday morning, approximately $1.6 million had been traded in Kalshi's women's singles champion prediction market.

Sports Prediction Market Expansion Accelerates

The US Open deal is part of a broader trend of prediction market operators aggressively expanding into mainstream sports.

Just days earlier, Kalshi announced partnerships with five Major League Baseball teams: the Boston Red Sox, Los Angeles Dodgers, San Diego Padres, Atlanta Braves, and San Francisco Giants. Kalshi said baseball trading volume on its platform surged 36-fold year over year.

Both Kalshi and Polymarket are official partners of the National Hockey League (NHL). Polymarket has also struck partnerships with several major sports leagues, including a league-wide deal with MLB.

Sports-related products have become a key driver of prediction market trading volume. According to The Block data, combined trading volume across Kalshi, Polymarket, and Polymarket US reached $41.2 billion this month, with Kalshi accounting for $33.7 billion of that total.

Regulatory Uncertainty Remains

While sports organizations are rapidly embracing prediction markets, the regulatory landscape remains murky.

Kalshi is engaged in legal disputes with multiple state regulators over whether state gambling laws can be applied to sports event contracts overseen by the U.S. Commodity Futures Trading Commission (CFTC). On Friday, the Ninth Circuit Court of Appeals ruled in a case against Nevada that the state may enforce its gambling laws against Kalshi's sports event contracts. The court found that Kalshi had not sufficiently demonstrated that federal commodities law preempts Nevada's gambling regulations.

The ruling directly conflicts with an earlier decision by the Third Circuit Court of Appeals that barred New Jersey from regulating Kalshi's sports contracts. The debate over regulatory authority between federal and state governments is expected to continue for the foreseeable future.

Despite this, sports organizations continue to enter the prediction market space. With the US Open deal, tennis is expected to emerge as a major new battleground for the prediction market industry.

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