The 2026 World Cup is doing for prediction markets what the 2024 election did: sending through-the-roof numbers. Polymarket’s trading volume has surged 300% on World Cup-related markets, while Kalshi’s aggregated open interest hit a record $1.16 billion last week.
The $1.16 billion OI figure marks the first time Kalshi’s open interest crossed the billion-dollar threshold. It’s a milestone that underscores how prediction markets have grown from niche crypto experiments into mainstream financial platforms.
The World Cup effect isn’t hard to explain. Sports betting markets have always been massive, and prediction markets offer a regulated alternative with transparent odds. With legal sports betting still unavailable in many US states, platforms like Polymarket and Kalshi fill a real demand.
Kalshi, which has had its own legal battles with US states over whether its sports markets constitute unlicensed gambling, seems to be winning the volume war. Its partnership with Robinhood gives it access to a massive retail user base that Polymarket can’t match in the US.
The World Cup boom is also drawing attention from mainstream financial players. With Cboe entering the space and Meta reportedly building an app, the prediction market sector is heading for a crowded — and potentially volatile — future.
