In September 2025, Kalshi and Polymarket, two prediction markets, had a combined trading volume of $1.44 billion, which is a record for the sector of the prediction markets for a single month. The achievement is a good indication of the growing interest of both the mainstream and institutional investors in the derivative exchange platforms based on predictions, as the two firms have completed significant funding rounds this month.
Polymarket forked out $2 billion for the Intercontinental Exchange (ICE) at a $9 billion valuation, whereas Kalshi managed to close a $300 million round at a $5 billion valuation, according to The Block’s Data and Insights report. Bloomberg wrote that after the funding event, Polymarket’s CEO Shayne Coplan is the youngest self-made billionaire.
In a remarkable turnaround, Kalshi surpassed Polymarket with a 60% market share in September, thus, the overall trend where Polymarket had led total trading volumes has been reversed. The analysts said that the reason for the dramatic rise is the recent Kalshi integration with Robinhood, which enables a user to access prediction markets directly within the trading app’s interface.
The wave of institutional money is a turning point for prediction markets, a sector that was once the niche of Web3. By collaborating with Robinhood, Kalshi has opened the door to millions of retail traders, thereby connecting the traditional finance world with blockchain-based speculation.
Nevertheless, these two platforms have substantial differences in their technical infrastructure. Kalshi is an off-chain operation, with data that is only accessible through centralized APIs, which has led some analysts to question how transparent it is about its trading volumes. In contrast, Polymarket is a fully on-chain platform, and all trades are verifiable via public blockchain records — a fact that has made it a preferred venue among crypto-native users and data transparency advocates.
One major factor in their record-breaking trading month is the wider industry trend where prediction markets are increasingly popular as a source of speculation and a tool for hedging. In turn, institutional participation and strategic integrations are propelling the adoption of new users and thus, Kalshi and Polymarket are becoming the two main players in the Web3 financial landscape that is still evolving.
The rapid expansion of both companies is a clear indication of the increasing confidence of the investors that blockchain-based prediction markets could be a vital element in the future of decentralized finance and event-based trading.
