Kalshi and Polymarket August trading volume drops 14.5%, marking the first monthly decline in a year.

Huo Xing Finance reports, according to The Block data dashboard, the combined trading volume of Kalshi, Polymarket, and Polymarket US in August decreased by 14.5% month-over-month to $45.33 billion, marking the first monthly decline in a year. Kalshi’s trading volume in August was $37.17 billion, down 7.3% from $40.1 billion in July; the combined trading volume of Polymarket and its U.S. platform was $8.16 billion, down 36.7% from $12.89 billion in July. The August decline followed a summer surge in prediction market activity driven by the World Cup (June 11 to July 19), but August trading volume remained significantly higher than the $25.66 billion recorded in May. Meanwhile, Kalshi and Polymarket are facing increasing scrutiny from U.S. state regulators, particularly regarding sports-related contracts, with over a dozen states having taken enforcement actions or filed lawsuits against the platforms. Last week, Connecticut sued Kalshi seeking to block the platform from offering sports contracts. Despite escalating legal disputes with state regulators, Kalshi is expanding its presence in the sports sector, recently signing an agreement with the United States Tennis Association to become the exclusive prediction market partner for the U.S. Open. Additionally, earlier this week, Kalshi permanently banned former U.S. Congressman George Santos—the first such permanent ban—in response to his violation of platform rules by trading bets on whether he would attend the State of the Union address, resulting in a fine exceeding $710,000.