Kalshi Surpasses Polymarket in Prediction Market Volume Amid U.S. Trading Surge

Kalshi has taken the lead in the on-chain prediction market sector, posting weekly trading volumes above $500 million and an average open interest of roughly $189 million, outpacing competitor Polymarket, according to Dune Analytics data.

From Sept. 11 to 17, Kalshi captured 62% of total sector volume, compared with Polymarket’s 37%. Kalshi’s higher weekly trading pace and open interest indicate faster turnover and more active trading, while Polymarket’s longer-duration markets keep user funds locked for extended periods.

The open interest-to-volume ratio illustrates this difference: Polymarket averaged 0.38, whereas Kalshi stood at 0.29, suggesting that Kalshi users engage in more frequent trading.

Despite trailing in volume, Polymarket is expanding its U.S. footprint. The platform completed its acquisition of regulated derivatives exchange QCX, marking its reentry into the U.S. market. Additionally, Polymarket has launched earnings-based markets in partnership with social investing platform Stocktwits, enabling investors to hedge earnings risk and gauge real-time market sentiment.

With Kalshi leading in trading activity and Polymarket bolstering its regulatory presence, the U.S. prediction market landscape is entering a competitive phase as both platforms aim to capture institutional and retail interest.