Kalshi gains 3 million users amid World Cup gambling

Spain has won the 2026 FIFA World Cup – and millions of new Kalshi users either won or lost money betting on the game.

According to prediction market Kalshi, the platform brought in 3 million new users during the World Cup tournament, which kicked off on June 11 and ended with the Spain vs. Argentina final on July 19.

In addition to the millions of new users, the company said that the World Cup broke a platform record for the most money traded in a single market. Kalshi says more than $1.2 billion in trades, the term the company uses to describe bets, were made to predict the winner of the World Cup.

Kalshi had a large presence throughout the World Cup. The company partnered with stars of the sport, such as Luka Modrić of the Croatia national team, who served as a brand ambassador and appeared in a commercial. Kalshi also had a partnership with the Argentina national team and received a featured post for the brand on Lionel Messi's Instagram account, which has over 512 million followers.

A commercial featuring A-lister Timothée Chalamet also appeared frequently in the U.S. market.

Despite their constant presence throughout the tournament, neither Kalshi nor its largest competitor, Polymarket, were official sponsors of the FIFA World Cup. A much smaller, new prediction market called ADI Predictstreet was deemed the "Official Prediction Market Partner of the FIFA World Cup 2026." However, Kalshi even found a way in there. Kalshi partnered with ADI Predictsteet in co-branded ad placements. In addition, website visitors from markets that ADI Predictstreet were not legally allowed to serve were told to visit Kalshi to place their trades in a prominent banner featured on ADI Predictstreet's homepage.

Prediction markets like Kalshi have been heavily criticized as they've blown up in popularity. There have been numerous alleged instances of illegal insider trading on these platforms. Critics have also pointed out how prediction markets allow users to trade on topics that could potentially lead to dangerous results. Gambling can also be very addictive, which is one reason sports betting is regulated so heavily.

Some U.S. states have also taken aim at sports trading on prediction markets, specifically. These states have argued that prediction markets are running illegal sports betting operations as they seek to curb activity on these platforms in the courts.

For now, though, it seems prediction markets like Kalshi continue to grow with every major event, such as the World Cup. At this point, it's a sure bet.