Prediction Markets Kalshi, Polymarket Hit $50 Billion Trading Milestone
Kalshi and Polymarket achieved a combined $50.6 billion in trading volume during July, marking an all-time high for prediction market platforms and a 7.8% increase from June’s $47 billion. Kalshi held the dominant position with $37.7 billion in volume, representing a 14% jump from the previous month. The Kalshi prediction market and its competitor saw substantial activity driven by the World Cup tournament, which ran from June 11 through July 19. Kalshi’s Spain-Argentina final market alone generated close to $1.9 billion, while Polymarket’s tournament winner contract attracted approximately $4 billion. Since the tournament concluded, both platforms have seen a significant declines in trading activity.
Kalshi and Polymarket Achieve Record $50.6 Billion Trading Volume
The Block’s data reveals Kalshi supplied roughly 74.5% of the three exchanges’ combined total, extending its lead over both versions of Polymarket. Polymarket US posted the strongest monthly growth among the three venues, with volume increasing 54% to $5 billion. In contrast, volume on Polymarket’s international platform declined 26% to $7.9 billion.
Combined volume across the two Polymarket businesses fell from about $14 billion in June to $12.9 billion in July. The U.S. platform gained activity without fully offsetting the drop recorded by the international exchange. Polymarket US removed its waitlist in May, opening the platform to any U.S. user and providing domestic traders a legal on-ramp they previously lacked.
The current dashboard uses a higher June baseline of $46.95 billion, showing that historical totals were updated as more trading data became available. Combined monthly global trading volume on these platforms rose from less than $5 billion in September 2025 to about $24 billion in April 2026. In April 2026, Polymarket US saw $1.3 billion in trading volume, compared with $9 billion on Polymarket International.
Sports, politics and cryptocurrency represent the topics with the highest volume on both major prediction markets.
World Cup Fuels Trading Surge Before Sharp Post-Tournament Decline
The 2026 FIFA World Cup generated $20 billion in on-chain prediction market volume since January, with approximately $5.7 billion occurring during the tournament’s five active weeks. According to data shared by Kalshi, the contract for the Argentina-Spain final reached $1.27 billion in trading volume. Total trading across World Cup contracts exceeded $25 billion, dwarfing the roughly $2 billion recorded for the NBA finals and $1 billion for the Super Bowl.
Kalshi and Polymarket spent hundreds of millions of dollars on World Cup advertising and sign-up bonuses, featuring pitch-side signage at the final and national television campaigns. As a result, the Kalshi prediction market attracted 3 million new users during the tournament. Female users grew 106%, more than twice the 54% growth rate among male users.
However, open interest across all three platforms fell from approximately $2 billion at the start of July to $1.2 billion by month’s end, a drop of roughly 40% as tournament contracts settled. Sports’ share of Kalshi’s volume declined from 70-85% during the World Cup to roughly 60% after the final, while Polymarket’s sports share fell from a peak of 84% to around 50%. Weekly trading figures on Kalshi after the final stayed above pre-June baselines.
New York Targets Kalshi Prediction Market with $36 Billion Lawsuit
New York Attorney General Letitia James filed a lawsuit against Kalshi on July 31 in Manhattan state court, alleging the platform operates an illegal gambling business in violation of state laws. The complaint claims Kalshi accepts wagers without registration from the New York State Gaming Commission, bypassing licensing requirements, consumer protections, and tax obligations that fund public schools and problem gambling programs.
The state seeks a permanent injunction, restitution to users, a $100,000 penalty for each sports wagering attempt, and fines totaling three times the company’s gains while allegedly operating illegally. These penalties could reach $36 billion.
“No matter what they call themselves, prediction markets like Kalshi are gambling platforms, plain and simple,” James stated. Governor Kathy Hochul added that the action aims to stop illegal behavior and enforce compliance with state law.
Kalshi board member Brian Quintenz characterized the lawsuit as “an unhinged, and extraordinarily egregious piece of lawfare” designed to shut down prediction markets entirely. The Commodity Futures Trading Commission filed for a temporary restraining order against New York’s enforcement actions, following an April lawsuit requesting a permanent injunction. CFTC Chairman Michael Selig accused James of seeking “an unprecedented sudden shutdown of prediction markets nationwide”.
Specifically, 44 state attorneys general challenged the CFTC’s authority over sports-related event contracts. The lawsuit targets not only sports offerings but also elections and culture contracts.
