TLDR
- Kalshi and Polymarket combined volume fell 14.5% in August to $45.33 billion.
- The decline marked the first month-over-month drop in prediction market volume since August 2025.
- Kalshi recorded $37.17 billion in August volume, down 7.3% from July.
- Polymarket and Polymarket US volume dropped 36.7% to a combined $8.16 billion.
- The slowdown followed strong World Cup-driven trading activity during June and July.
Kalshi and Polymarket recorded a sharp drop in combined trading volume in August, ending a year-long run of monthly growth. Total volume across Kalshi, Polymarket, and Polymarket US fell 14.5% to $45.33 billion, according to The Block’s data dashboard.
The decline followed July’s record $50.59 billion in combined volume. Activity had surged during the FIFA World Cup, which ran from June 11 to July 19 and drove strong demand for sports prediction contracts.
Kalshi and Polymarket Volume Falls in August
Kalshi posted $37.17 billion in August trading volume, down 7.3% from $40.1 billion in July. Polymarket and Polymarket US recorded $8.16 billion combined, a 36.7% decline from $12.89 billion.
Even after the monthly drop, August activity remained far above May’s $25.66 billion total. July volume had also risen 7.8% from June’s revised $46.95 billion, showing how quickly World Cup-linked activity lifted the market.
World Cup Boost Fades From Prediction Markets
Sports contracts have driven most recent activity on Kalshi, accounting for more than 88% of trading. Kalshi also represented about 74.5% of the combined July volume across the major prediction market platforms.
The slowdown appeared more severe on Polymarket’s offshore platform. Still, sports markets remained active. NFL preseason contracts generated $167.8 million across Kalshi, Polymarket Global and Polymarket US in the week ending August 16.
Regulatory Pressure Builds Across U.S. States
Kalshi and Polymarket also face growing legal pressure from state regulators over sports-related contracts. More than a dozen states have taken enforcement action or filed lawsuits against the prediction market platforms.
Connecticut sued Kalshi last week in an effort to block sports contracts. The case extends an ongoing dispute between the state and the CFTC-regulated exchange over whether such contracts fall within federal or state authority.
Kalshi Expands Sports Business Despite Pullback
Kalshi continued expanding its sports presence despite the lower monthly volume. The company recently signed an agreement with the U.S. Tennis Association to become the exclusive prediction market partner of the U.S. Open.
Kalshi also reached a weekly milestone near the end of August. Contract volume topped $10 billion for the first time in the week ending August 30, reaching $10.17 billion despite the broader monthly decline.
The platform permanently banned former U.S. Rep. George Santos after he traded on a contract tied to his State of the Union attendance. He was fined more than $71,000.
