Total monthly trading volume across major prediction market platforms Kalshi, Polymarket, and Polymarket US reached a historic all-time high of $50.59 billion in July 2026. Data from The Block indicates a 7.8% month-over-month increase from June’s revised $46.95 billion total, driven primarily by massive retail and institutional participation in sports event contracts tied to the 2026 FIFA World Cup.
Kalshi Dominates Market Share as Polymarket US Accelerates
Kalshi maintained its position as the largest single venue, generating $37.7 billion in volume for July, a 14% month-over-month increase. The exchange accounted for nearly three-quarters of the combined volume across the three tracked platforms.
Meanwhile, a noticeable shift occurred between Polymarket’s international and US-regulated entities. Volume on the main offshore Polymarket platform contracted by 26% to $7.9 billion. Conversely, Polymarket US saw trading activity surge 54% to reach $5 billion for the month. The growth follows Polymarket US lifting its waitlist restrictions in May, allowing domestic traders to transition from unhosted or offshore access to a platform regulated by the Commodity Futures Trading Commission (CFTC). Together, the two Polymarket entities posted a combined volume of $12.9 billion.
World Cup Catalyst and Post-Tournament Cool-Down
The primary catalyst for July’s record-setting performance was the FIFA World Cup, which ran from mid-June through July 19. Individual event contracts tied to the tournament drew unprecedented liquidity. Kalshi’s single market on the final match between Spain and Argentina processed roughly $1.9 billion in volume, while Polymarket’s flagship contract predicting the overall tournament winner attracted approximately $4 billion.
Following the conclusion of the World Cup, overall capital retention and open interest contracted sharply. Open interest across Kalshi, Polymarket, and Polymarket US dropped from approximately $2 billion at the start of July to $1.2 billion by month-end, signaling a temporary post-tournament cool-down in capital deployment even as monthly turnover set new benchmarks.
Ongoing Regulatory Friction and Preemption Battles
Despite record activity and expanding domestic access, prediction markets remain locked in regulatory friction across the United States. Over a dozen state gaming regulators have taken aggressive legal steps against event contract trading, alleging that sports-related contracts constitute unlicensed gambling rather than financial derivatives.
In response, prediction market operators alongside the CFTC have fought back in state and federal courts, asserting that CFTC registration grants exclusive federal oversight that preempts state gaming statutes. With state enforcement escalating and federal preemption battles coming to a head in appellate courts, the long-term regulatory framework governing US event contracts remains a central focus for market participants.
