Prediction Market Volume Reaches $120.7 Billion in October, Up 64%

U.S. prediction market volume reached $120.73 billion in October 2026 , up 64.1% from $73.58 billion in September, according to DeFi Rate's analysis of trading activity across eight exchanges. Kalshi led with $98.15 billion, accounting for 81.3% of reported volume, followed by Polymarket US at $14.77 billion. Together, the two exchanges generated $112.92 billion, or 93.5% of the October total. October's growth extended beyond the two market leaders. Novig and Underdog more than doubled their monthly trading volume, while identified combo volume across five exchanges increased 93.2% to at least $79.46 billion.