Kalshi Tops $4B in Weekly Notional Volume, Pulling Ahead of Polymarket

Kalshi recorded more than $4 billion in weekly notional volume over the past week, up from $54.5 million a year earlier. The same week, Kalshi posted $4.1 billion versus Polymarket's $2 billion, putting Kalshi at about 2.05x Polymarket's weekly volume. The gap widened after Polymarket's April 28 V2 upgrade, which paused trading for roughly an hour and removed open limit orders.