FIFA World Cup predictions have become the biggest business in prediction markets. Polymarket's tournament winner market alone holds $2 billion in bets, while Kalshi runs 48 markets on the same question and banks the industry's largest fees. BeInCrypto's Dune dashboards across three venues show where volume, fees, and leftover crypto bets sit. According to Binance Research, prediction markets turned over a record $31.2 billion in May, up roughly 15% from January. Kalshi holds 58% of that flow, Polymarket 28%, with industry open interest reaching $1.3 billion. Sports trading volume reached $10.44 billion on Kalshi in May, far surpassing elections at $173.66 million. Polymarket's World Cup Winner market has $2 billion in lifetime volume and $436 million in liquidity, while Kalshi's equivalent has $182.3 million across 48 markets. Both platforms price Spain as favorite at 17% odds. Sports have led Polymarket all year, peaking at $8.77 billion in March, and even as total volume cooled to $5.91 billion in June, sports share climbed to 56.5%. In fees, Kalshi collected $137.86 million in May versus Polymarket's $28.07 million. Smaller venue Opinion shows sports at 99.4% of activity by June 1, replacing crypto and politics. The record May arrived while overall activity was already cooling, raising questions about whether the prediction market boom has peaked.

Key facts

• Prediction markets hit $31.2B in May 2026, up 15% from January.
• Kalshi holds 58% market share, Polymarket 28%, others 14%.
• Polymarket's World Cup Winner market has $2B volume and $436M liquidity.
• Kalshi's 48 World Cup markets total $182.3M; fees 5x Polymarket's.
• Sports dominate: 56.5% of Polymarket volume in June, $10.44B on Kalshi in May.