Woofun AI reports that Polymarket's soccer trading volume exceeded $2 billion in the ten days preceding the World Cup, marking a 300% increase from the prior period. Average daily volume climbed from $53 million to approximately $220 million.

Meanwhile, Kalshi's open interest reached a record $1.16 billion last Thursday, surpassing the $1 billion threshold for the first time and growing 350% year-to-date. Although Polymarket's overall open interest remained stable, its U.S. branch saw only moderate growth, failing to match April 2026 highs. Kalshi's open interest expanded faster than trading volume, suggesting users hold positions longer and maintain larger directional bets. Its CFTC-regulated status and direct USD deposit gateway have attracted U.S. institutions and high-net-worth dollar investors.