Kalshi and Polymarket record $1.4 billion trading month as institutional backing surges

Prediction markets continued to run hot last week, with Kalshi and Polymarket both announcing new raises. Polymarket raised $2 billion from the Intercontinental Exchange (ICE), placing the platform at a $9 billion valuation, while Kalshi secured $300 million at a $5 billion valuation.

The funding rounds have minted at least one new billionaire, with Bloomberg reporting that Polymarket's Shayne Coplan became the youngest self-made billionaire following the raise.

Last month, Kalshi captured a peak 60% market share against Polymarket in September, marking a significant reversal from earlier in the year when Polymarket dominated trading activity. The two platforms combined for a record-setting $1.44 billion in volume during September, reflecting surging mainstream interest in prediction markets as a new speculative venue.

An important technical distinction separates the two platforms’ approaches to market infrastructure. Kalshi operates off-chain, with market data accessible only through traditional APIs — leaving some observers unsure how to independently verify the figures. Polymarket, by contrast, runs fully onchain, where all markets and positions are publicly viewable on the blockchain.

Kalshi's recent volume surge is partly linked to its partnership with Robinhood, which now allows users to place sports bets through Kalshi directly within the Robinhood interface. This integration provides Kalshi with access to Robinhood's substantial retail user base, potentially explaining the platform's growing market share.

The partnership demonstrates how prediction markets are becoming increasingly embedded in mainstream trading platforms, moving beyond crypto-native audiences. 

This is an excerpt from The Block's Data & Insights newsletter. Dig into the numbers making up the industry's most thought-provoking trends.