Kalshi US Open Deal Highlights Tennis Prediction Market Boom

Kalshi and the USTA announced a partnership on August 31, making Kalshi the official prediction market partner of the US Open. The major US prediction market operator has been brokering many new partnerships in recent weeks, having just secured multi-year deals with Major Baseball Clubs, and linked up with NASDAQ and major sports data provider Genius Sports. And now the sports-oriented prediction market has set its sights on tennis.

But this is not just another sports partnership, at least, not on the surface. Tennis may fall second fiddle at most sportsbooks to football and basketball in America, perhaps even behind baseball too, but they are pretty well covered at prediction markets. And can boast massive trading volume, even for events outside the US Open and other Grand Slams.

Kalshi USTA Partnership

This Kalshi and USTA partnership is a multi-year deal, which will start with the upcoming 2026 US Open. This will mean Kalshi can advertize its products across the tournament’s digital platforms, at on-court signage, and also have digital rights to market with US Open signage. Kalshi, a prediction market that needs no introduction, is extremely specialized towards sports. This is something that has made the prediction market so popular in the US, and has drawn many copycats and other big players trying to mimic their parlays, props trades, and other sports betting-style products.

And Kalshi is no stranger to taking the spotlight where big events are concerned. While ADI PredictStreet was the official betting partner for the FIFA World Cup, within a few weeks of the tournament, Kalshi secured a deal with ADI PredictStreet to brand its name alongside the Gibraltar-licensed prediction market.

But this is not going to be a one-sided deal. Not by any means. Because with this agreement, Kalshi will also have to adhere to a comprehensive integrity framework, set out by the US Open to protect the competition. That will mean, no prediction markets contracts at Kalshi on:

• Player injuries
• Umpire decisions
• Code violations
• Other integrity-risk trades

Recent Kalshi Partnerships

This summer has been something of a partner brokering shopping spree for Kalshi. Just a few days before linking forces with the USTA, Kalshi also made multi-year partnerships with MLB teams, so it is now partnered with the Boston Red Sox, Atlanta Braves, San Francisco Giants, Los Angeles Dodgers and San Diego Padres. And going back a few weeks earlier, Kalshi also struck an alliance with Genius Sports. This gave Kalshi access to official real-time sports data, as well as all the media and marketing services.

Having Genius as a data provider can only bolster Kalshi’s integrity, as they have a reliable source for their information, which is used to settle contracts and helps reduce any disputes.

Then there is Nasdaq. Kalshi’s multi-year partnership with Nasdaq, announced on August 10, was aimed at strengthening the prediction market’s trade surveillance capabilities. By integrating Nasdaq’s real-time market surveillance technology, which is already used by more than 50 exchanges and 20 international regulators, Kalshi has better monitoring to detect insider trading, market abuse and outcome manipulation. These are all vital to building trust in a market that has been littered with scandals and ongoing legal controversy.

Importance of Tennis

If you look at the traditional US sports betting market, tennis is nowhere near the level of football and basketball. The NFL, NBA and college football generate enormous betting interest, with massive betting handles for the Super Bowl, and a flurry of betting volume during March Madness. Tennis, historically, has never reached these highs – even for the major Grand Slam events.

But tennis is actually a surprisingly good fit for prediction markets. In Kalshi’s words: Tennis fans have embraced prediction markets, with trading volume up 25x year over year.

It attributes this to the structure of tennis games, the binary game outcomes, how information is collected and consumed by both odds generators and punters, and the highly volatile game dynamics.

Why Tennis is Just Different From Other Sports

Tennis is a game that is packed with statistics that can be very volatile, something that a lot of microbetting specialized sportsbooks have picked up on. Now this also works for prediction markets. If you just consider binary outcomes (yes/no, win/lose), you can break matches down into sets and games. Then, you can also do over and under Yes/No outcomes for games at Kalshi. There are plenty of markets to explore:

• Moneylines
• Spreads
• Totals
• Set Winner
• Exact Score
• Alternate Line Totals
• Props

But here is where it gets interesting. One of the key formulas of prediction markets like Kalshi is the historical line movements – driven by public demand. You get a timeline where you can see Yes/No buying volumes and the resulting price/risk percentages. Games can change the momentum, within sets, players can repeatedly take the lead, lose it, regain it, and so on. Every game can impact the price, and this entertains value bettors.

Throw in the opportunities for cashing out or hedging bets, and these expert bettors have a lot to think about with tennis.

ATP Polymarket Deal

And Kalshi is not the only prediction market that has recognized the potential in tennis. On August 3, Polymarket became the official prediction market provider of the ATP Tour, in a deal that also covers the ATP Challenger Tour. Polymarket secured exclusive streaming rights for ATP Tour and ATP Challenger Tour matches within the prediction-market category, allowing eligible US users to watch matches alongside relevant prediction markets. And where Kalshi is partnered with Genius Sports as an official data provider, Polymarket has their own deal with Sportradar to power market settlements.

Kalshi has the US Open, Polymarket has ATP. These are the two biggest prediction markets in the US, and the close proximity of their tennis-related partnerships just show how important the sport is to the industry.

What About Walkovers or Injuries

Tennis does come with some unusual challenges for prediction markets, and one of the biggest is walkovers. A player can withdraw before a match starts, meaning there is no actual contest to determine the outcome. This can create problems for markets because a contract asking who will win the match technically never gets its real settlement. Different platforms therefore have specific rules for these situations.

Kalshi’s approach uses a fair price for ATP and WTA walkovers, while ITF walkovers resolve at $0.50. If a match has already started and a player retires, the player who advances is generally treated as the winner for settlement purposes. These rules may sound like a relatively minor detail, but they become important when large amounts of money are being traded. And the same goes for injuries. A prediction market cannot simply offer contracts on every conceivable event that happens during a match. The US Open partnership specifically addresses this, with markets relating to player injuries, umpire decisions and code violations restricted because of their potential integrity risks.

This could ultimately become one of the biggest challenges for sports partners and prediction markets. It is all about making products that are fair to both the traders and also spare the integrity of the sport. The partnerships therefore are not just about handing over digital marketing rights or propelling one prediction market towards one league, one club, or one partnered organization. It is about establishing some base rules for the prediction market too.

Prediction Markets Holding Ground

Kalshi and Polymarket have been expanding their partnerships, new prediction market operators keep cropping up, and in the meantime the state regulators and federal authorities are in a legal limbo. Prediction markets are definitely one of the most controversial betting-style products in the US, and for the time being there isn’t any really major market abroad. Canada recently tightened its rules on prediction markets and across Europe, more regulators have either banned or temporarily blocked prediction markets as they consider how (or if) they can be regulated.

Deals like this one, between Kalshi and USTA, help give prediction markets more of an established standing in the US. But if one thing can be learned from sweepstakes casinos – the big hype before prediction markets – is that the tables can turn. A state that can figure out how to ban prediction markets, like what Minnesota tried to do, but was ultimately rebuffed by the federal government, could set a legal precedent. And then, just like what happened to sweepstakes casinos, it can create a domino effect that leads to the downfall of prediction markets.

But for the time being, it looks like Kalshi, Polymarket, and all the other prediction markets and sportsbooks with prediction market apps, are on the up and up in the US betting industry.