Prediction market volume drops 15% in August after World Cup surge

Combined trading volume on prediction markets Kalshi, Polymarket, and Polymarket US fell 14.5% in August to $45.33 billion, marking the first month-over-month decline in a year. Prediction markets are platforms where users bet on the outcome of real-world events, such as elections or sports.

Volume falls after World Cup-driven spike

The drop follows a surge in activity during the World Cup, which ran from June 11 to July 19. Despite the decline, August’s volume remained well above May’s $25.66 billion.

Kalshi recorded $37.17 billion in August, down 7.3% from July’s $40.1 billion. Polymarket and its U.S. platform saw a combined $8.16 billion, a 36.7% drop from $12.89 billion in July.

Key numbers

• Combined volume: $45.33 billion (down 14.5%)
• Kalshi volume: $37.17 billion (down 7.3%)
• Polymarket + Polymarket US volume: $8.16 billion (down 36.7%)

Regulatory pressure continues

Both platforms face increased scrutiny from U.S. state regulators, particularly over sports-related contracts. Over a dozen states have taken enforcement action or filed lawsuits against Kalshi and Polymarket. Last week, Connecticut sued Kalshi to block sports contracts, escalating a months-long legal fight.

Despite regulatory challenges, Kalshi recently signed a deal with the U.S. Tennis Association to become the exclusive prediction market partner of the U.S. Open, which began on August 30. The platform also issued its first permanent ban to former U.S. Rep. George Santos for violating trading rules.

Sources

• The Block