Weekly prediction market volume has grown 73.2% since the last week of summer, extending the expansion into October. The latest weekly increase was 3%, compared with 12.6% a week earlier, as activity continued to set records despite slower growth. Kalshi set a daily volume record above $4 billion on October 11. Kalshi's weekly volume has risen 86.3% to $19.0 billion since the last week of summer. Polymarket's weekly volume increased 85% to $3.7 billion over the same period.