Prediction-market platforms such as Kalshi and Polymarket functioned as de facto sportsbooks during the 2026 World Cup, with sports contracts now accounting for more than 85 percent of Kalshi’s total volume, according to a June 2026 study by HTX Research.
HTX Research is the research arm of cryptocurrency exchange HTX, formerly known as Huobi. The study said the platforms have absorbed billions of dollars in wagers across the United States and offshore while operating outside the integrity-monitoring and licensing obligations applied to regulated sports-betting operators.
Ahead of the opening match on June 11th — Mexico’s 2-0 win over South Africa at Estadio Azteca — cumulative trading on World Cup contracts across Polymarket and Kalshi neared $2 billion, the largest sports stress test prediction markets have faced, the study said. Polymarket’s “World Cup Winner” market had generated about $1.6 billion in cumulative volume since launching last year across 58 distinct markets, while Kalshi’s winner market stood at roughly $87.5 million across 424 World Cup-related contracts.
Institutional projections cited in the report vary. Research from Bookies.com and RotoWire puts total U.S. prediction-market volume for the tournament above $2.37 billion, while DeFiRate projects that Kalshi alone could contribute $1.47 billion. Under a consolidated estimate cited in the report, the tournament could drive up to $2.5 billion in volume, with the single “World Cup Winner” contract expected to reach roughly $253 million — already outpacing this year’s March Madness.
Volume overtakes traditional betting
Citing Pew data, the report said combined monthly volume on Kalshi and Polymarket rose from under $5 billion in September 2025 to about $24 billion in April 2026. Legal U.S. sports betting averaged roughly $14 billion in monthly handle last year, meaning prediction markets have overtaken regulated sportsbooks by that measure. Kalshi recorded $17.91 billion in nominal volume in May, its ninth consecutive record month, compared with Polymarket’s $7.08 billion over the same period.
A SEON survey referenced in the study found that about half of those planning to bet on the World Cup in the United States intended to use prediction markets. The report noted that such platforms allow anyone aged 18 or older to trade across all 50 states, setting a lower age and geographic threshold than most state sportsbook frameworks.
The integrity gap
Despite that scale, the platforms fall outside the integrity-monitoring requirements imposed on licensed operators. HTX Research said inside information on injury reports, starting lineups and referee assignments is “equally ripe for abuse” during the World Cup.
The report also pointed to growing scrutiny over material non-public information, including a U.S. Commodity Futures Trading Commission insider-trading alert in February 2026 involving a candidate who traded on their own election contract. It also cited an offshore Polymarket user who drew attention for accumulating large positions on the possible ousting of Nicolás Maduro between late 2025 and early 2026.
Regulators divided
The legal standing of the platforms remains contested, according to the study. Regulators in several states have issued cease-and-desist orders classifying them as “unregistered, illegal sports betting,” while Kalshi argues that it is regulated by the CFTC and therefore exempt from state gaming boards. Kalshi has sued the New York State Gaming Commission, while Minnesota, New Mexico and Nevada are reviewing the platforms’ status. Crypto.com’s head of prediction business has publicly maintained that prediction markets are not gambling or wagering.
In Asia, the regulatory divergence has already prompted action. Hong Kong halted its planned rollout of legal basketball betting, with the Home and Youth Affairs Bureau warning that launching the scheme could draw more attention to unregulated prediction-market platforms and indirectly fuel illegal gambling. Betting on sports through such platforms is illegal in the city, and the basketball betting scheme had been set to launch as early as September under the Hong Kong Jockey Club.
