Kalshi hits $17.91B May volume record as Polymarket falls to lowest since January
Kalshi recorded $17.91 billion in notional trading volume in May, its ninth consecutive monthly record and a 21% jump from April's then-record $14.81 billion, according to DeFi Rate's prediction markets volume tracker. Polymarket posted $7.08 billion for the same month, down 21% from its $10.57 billion March peak and its lowest monthly total since January. The World Cup drove a weekly volume high for Polymarket US. Kalshi's May total marks its first sustained monthly lead over Polymarket, building on its earlier crypto-volume flip this month. The divergence comes as DRW, Wintermute, and IMC establish dedicated market-making desks on both platforms.
Kalshi's ninth straight monthly record gives it hard volume evidence for its $1 billion Series F pitch that regulated markets can drain offshore liquidity. Any sustained gap threatens Polymarket's ability to match that valuation premium, especially after its eight-month growth streak ended earlier this month.
Becomes the fourth consecutive cluster of Kalshi volume dominance over Polymarket this month after the crypto flip, the weekly OI record, and the sustained monthly lead, cementing a run that now threatens Polymarket's investor narrative during Kalshi's Series F window.