Kalshi Dominates Prediction Market Volume Over Polymarket as US Trading Surges

Kalshi is establishing clear dominance in the prediction market sector, capturing a majority share of trading volume despite increased competition from platforms like Polymarket expanding into regulated US markets. According to Dune Analytics data from September 11-17, Kalshi accounted for 62% of total on-chain prediction market volume compared to Polymarket's 37%. Kalshi's weekly trading exceeded $500 million with average open interest of approximately $189 million, outperforming Polymarket's $430 million volume and $164 million open interest. The data indicates faster turnover on Kalshi (0.29 open interest-to-volume ratio) versus longer-term positions on Polymarket (0.38 ratio). Despite this, Polymarket is strengthening its US presence through its acquisition of regulated derivatives exchange QCX and has launched earnings-based markets in partnership with Stocktwits, enabling real-time market sentiment analysis and earnings risk hedging for stockholders.