Prediction markets achieved a historic milestone in July, recording $50.59 billion in combined monthly trading volume across Kalshi, Polymarket and Polymarket US, according to data published on August 3. This represents a 7.8% increase from June's revised total of $46.95 billion, with Kalshi leading at $37.7 billion while Polymarket US volume climbed 54% to $5 billion. The figures measure taker notional volume rather than exchange revenue, showing greater contract turnover and liquidity rather than new capital entering the platforms. Notional volume should not be treated as platform income, as traders can buy and sell the same contract multiple times before settlement.
The FIFA World Cup, which ran from June 11 through July 19, provided a significant boost to prediction market activity, with Chainalysis separately estimating that World Cup-related blockchain prediction markets generated $20 billion from January through the tournament's conclusion. More than 400,000 wallets produced $5.7 billion during the five-week competition, with World Cup markets representing approximately 63% of prediction-market activity during that period. Kalshi's market on the final between Spain and Argentina recorded approximately $1.89 billion in volume, with Spain winning 1-0. The World Cup figures are not directly comparable with the $50.6 billion monthly total, as Chainalysis examined on-chain markets while The Block's dataset combines centralized Kalshi activity with Polymarket's international and U.S. venues.
Polymarket US posted the strongest monthly growth of the three venues, with volume increasing 54% to $5 billion, while 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 platforms reached the volume record while facing conflicting legal decisions over federal derivatives regulation. On July 31, New York sued Kalshi, accusing it of running an illegal gambling operation and seeking to stop the platform from offering unlicensed event contracts. Four days earlier, a Minnesota federal judge temporarily stopped the state from enforcing its prediction-market law against Kalshi and Polymarket US, finding the platforms likely to succeed on federal preemption grounds.
Open interest across Kalshi and the two Polymarket platforms fell from around $2 billion near the start of July to approximately $1.2 billion by month-end, indicating that many positions settled or closed as the tournament ended. The decline shows that many positions settled or closed as the tournament ended, even though total monthly turnover reached a record. August data will provide the first full-month test without the World Cup, with the next question being whether sports, politics and economic contracts can preserve July's trading pace while New York and Minnesota cases move through court. The mainstream attention gained by prediction markets is evident in the valuations of major platforms, with Polymarket valued at $15 billion during funding discussions in April and Kalshi targeting a $40 billion valuation in its latest investment talks.
