Kalshi, Polymarket Volume Falls 15% in August, First Drop in a Year

Kalshi and Polymarket allow traders to buy contracts tied to outcomes in politics, sports and other real-world events, with prices serving as market-implied probabilities. Their growing scale underscores prediction markets’ shift from niche wagering products toward a broader financial and consumer category, drawing closer scrutiny of liquidity, market structure and regulation as more users and capital enter the sector.

Combined trading volume at Kalshi and Polymarket exceeded $50.6 billion in July 2026, setting a monthly record as World Cup-related contracts helped drive activity. Polymarket’s US market posted a 54% increase from June, while volume on its main platform fell 26% over the same period. The divergence suggests that fresh demand was concentrated in the regulated US offering and major sports events rather than spread evenly across Polymarket’s operations.

Prediction markets let traders wager on real-world outcomes, making the 2026 FIFA World Cup a major test of the sector’s ability to attract mainstream users. Kalshi and Polymarket now account for more than 95% of the market, cementing a duopoly in which scale, consumer reach and marketing spending increasingly determine which platform converts attention into trading activity.

After the tournament concluded in July 2026, Kalshi reported $54.338 billion in total platform trading volume, 2.6 times Polymarket’s tally. Kalshi also led in app downloads and aggregate trading value, helped by heavy advertising spending. Polymarket continued to draw more website visits, but that traffic did not translate into a volume lead, leaving Kalshi ahead on the industry’s most closely watched commercial measures.

Prediction markets allow users to trade contracts tied to the outcomes of sporting, political and other events, with prices reflecting the market-implied probability of each result. Betting demand generated by the 2026 FIFA World Cup rapidly expanded Kalshi and Polymarket, bringing greater scrutiny to their liquidity, compliance and regulatory disputes across U.S. states.

Kalshi and Polymarket recorded a combined $44.8 billion in trading volume in June 2026, up 75% from May. Kalshi's monthly volume surged 87.4% to a platform record. Polymarket also returned to growth, supported by World Cup enthusiasm and U.S. market demand, though both companies continued to face regulatory challenges from several U.S. state governments.

Polymarket and Kalshi are prediction-market platforms that let users trade contracts based on the outcomes of political, economic and other events. Their cumulative trading volume has surpassed $150 billion, underscoring the sector's emergence as a major fintech segment. Kalshi has taken the lead in the U.S. market with authorization from the Commodity Futures Trading Commission.

Polymarket and Kalshi recorded a combined $21.9 billion in monthly trading volume in April 2026, an all-time high. However, Polymarket's monthly volume fell for the first time since August 2025, allowing Kalshi to overtake it in scale. Polymarket has also partnered with Chainalysis to strengthen compliance as it continues seeking to reopen trading to U.S. users.