March 2026 was the biggest month on record for U.S. prediction markets, with Kalshi finishing at $13.07 billion in notional volume and 88.4 million transactions, up 25% from February on both measures. Polymarket followed with $10.57 billion in notional volume and 115.4 million transactions, a 33% and 43% MoM increase, marking the second consecutive month of all-time highs for both platforms. The final week of March showed more nuance, as Kalshi rose to $2.90 billion in notional volume (+6.4% WoW) on the back of the NCAA Men’s Final Four, while Polymarket slipped to $1.97 billion (-12% WoW).
That divergence was driven largely by category exposure: crypto markets on Polymarket fell about 24%, while Kalshi’s politics markets jumped roughly 36% WoW on government shutdown and cabinet news. Kalshi remains below its all-time peak of $3.40 billion set in the NCAA-heavy week of March 16. Kalshi’s lead over Polymarket in notional volume widened over the six weeks, rising from about $329 million in late February to roughly $932 million in the final week of March. Kalshi captured 55.3% of combined K+P notional volume for the month, down slightly from 56.8% in February, but its edge in high-profile sports markets remains the defining competitive advantage.
Polymarket, meanwhile, processed 115.4 million transactions in March, about 31% more than Kalshi, with an average trade size near $92 versus Kalshi’s around $148. On a broader note, the regulatory backdrop shifted this week, with a Nevada judge extending the ban on Kalshi operating in the state and the CFTC filing lawsuits against Illinois, Arizona and Connecticut to defend exclusive authority over prediction markets. The federal-versus-state regulatory battle is now in active litigation, an overhang for the industry that could shape market access and platform strategy well into 2026 and beyond. March set the ceiling; April will tell us whether it’s a floor to grow from.
Leave a Reply