TLDR
- Prediction markets combined for $50.6 billion in July trading volume, a new record.
- Kalshi led all platforms with $37.7 billion, about 74.5% of the total.
- Polymarket US volume jumped 54% to $5 billion in July.
- Open interest fell to $1.2 billion as World Cup contracts settled.
- New York sued Kalshi while a Minnesota judge blocked state enforcement against the platforms.
Prediction markets set a new record in July. Combined trading volume across Kalshi, Polymarket and Polymarket US reached $50.6 billion. The data was published on August 3.
The total rose 7.8% from June’s revised figure of $46.95 billion. That number was higher than the $44.8 billion first reported for June. More trading data became available after the month ended, which pushed the baseline up.
Kalshi stayed the largest platform by far. It generated $37.7 billion in July, up about 14% from June. That gave Kalshi roughly 74.5% of the combined total across all three venues.
Polymarket’s two platforms combined for $12.9 billion. That was down from about $14 billion in June. The drop came even though one of the two Polymarket platforms grew.
Polymarket US Growth Outpaces Offshore Decline
Polymarket US posted the strongest growth of the three exchanges. Its volume climbed 54% to $5 billion in July. The platform removed its app waitlist in May, opening access to more U.S. users.
Polymarket’s international platform moved the opposite direction. Volume there fell 26% to $7.9 billion. The decline was large enough to more than offset the gains made by Polymarket US.
Rutgers University statistician Harry Crane has studied where Polymarket’s offshore volume comes from. He estimated that around 30% of that volume could originate from U.S. traders. His broader estimate ranged from 19% to 48%.
Crane said blockchain transactions do not show where a trader is located. That means his estimates are based on indirect data rather than confirmed customer records.
World Cup Contracts Drove Much of the Activity
The FIFA World Cup ran from June 11 through July 19. It created a steady stream of sports contracts that traders bought and sold throughout the tournament.
Kalshi’s market on the final between Spain and Argentina alone generated about $1.89 billion in volume. Spain won that match 1-0.
Chainalysis separately tracked blockchain-based prediction markets tied to the World Cup. It estimated $20 billion in related volume from January through the end of the tournament.
About 400,000 wallets produced $5.7 billion during the five-week competition, according to Chainalysis. World Cup markets made up roughly 63% of all prediction-market activity during that stretch.
These figures are not directly comparable to the $50.6 billion total. Chainalysis only tracked on-chain activity, while the wider dataset combines Kalshi’s centralized platform with both Polymarket exchanges.
Open interest across all three platforms fell as the tournament wrapped up. It dropped from around $2 billion in early July to about $1.2 billion by month’s end. That decline shows many positions closed out once World Cup contracts settled.
Trading volume is not the same as platform revenue or customer deposits. Traders can buy and sell the same contract multiple times before it settles. That activity raises volume figures without new money entering the platform.
Legal fights are also shaping the industry. On July 31, New York sued Kalshi, accusing it of running an unlicensed gambling operation. The state is seeking penalties, forfeiture and customer restitution, though the claims have not been proven in court.
Four days earlier, a federal judge in Minnesota issued a different ruling. The judge temporarily blocked the state from enforcing its prediction-market law against Kalshi and Polymarket US, citing federal preemption.
The judge noted that not every contract on these platforms may qualify as a federally regulated swap. Any final ruling could end up narrower than the temporary order.
August will be the first full month without World Cup contracts driving volume. Traders and platforms are now watching whether sports, politics and economic contracts can keep pace while the New York and Minnesota court cases continue.
