Sports Betting Drives Steep Rise of Prediction Markets

Prediction markets like Kalshi and Polymarket have risen to global prominence (and notoriety) quickly over the past year. Data by digital information provider The Block analyzed by Pew Research Center shows just how swiftly the firms' global trading volume has shot up to almost $25 billion as of April. The numbers also reveal that the meteoric ascent happened largely on the back of sports betting.

Polymarket and Kalshi became known as platforms to bet on almost everything, not just sports. Politics and cryptocurrency are the next biggest categories, but they made up only $2.7 billion and $3.2 billion in monthly trading volume most recently. This is compared to $15.5 billion in sports betting volume. Other prediction markets are even smaller, for example betting on what public figures will say in speeches (so-called mention markets) and betting on the weather, for example. However, smaller categories can balloon for specific events. The 2024 U.S. presidential elections are marked by a visible bump on the chart at a time when both prediction platforms were still awaiting their explosive growth.

Kalshi is the bigger platform between the two, trading almost $15 billion in April 2026, of which $11.5 billion was in sport betting. Polymarket is smaller at a monthly volume of $9 billion, of which only around $4 billion was in the sports segment. While Kalshi is regulated in the U.S. by the Commodity Futures Trading Commission, Polymarket's global platform is not and is only accessible via VPN from the United States. Polymarket has launched a platform conforming to U.S. law, but trading volume on there is still low, according to Pew, at $1.3 billion versus Polymarket International's $9 billion this April.