Prediction markets just crushed traditional sportsbooks in a massive $50 billion World Cup breakout

The 2026 FIFA World Cup was already set to be the biggest sports betting event ever staged on American soil. What nobody had fully pencilled in was that two prediction market startups would together challenge the entire established gambling industry for a piece of it.

The numbers are stark. Kalshi posted $31 billion in total notional trading volume in June, a more than 70% jump from May — with sports contracts accounting for around 85% of its trading, per Dune analytics. The company told CoinDesk that World Cup-specific volume on its platform has now reached $22.42 billion. Polymarket's international exchange set a new monthly record at $10.8 billion overall trading volume, while its regulated U.S. platform separately logged $3.5 billion, nearly double May's total. Rothera, a joint venture between Robinhood and Susquehanna International Group that only launched in June, processed $2 billion in its debut month and already accounts for 7% of the U.S. prediction market, according to Bank of America.

It’s worth noting that unlike traditional sportsbooks, prediction markets cover far more than sports — Kalshi and Polymarket both carry contracts on political elections, economic data and even reality TV shows like Love Island. U.S. legal sportsbooks, meanwhile, are projected to handle between $2.8 billion and $4.3 billion across the tournament's 104 matches. Kalshi’s World Cup-specific markets alone generated $7.4 billion in June before the group rounds were complete.

The ban that wasn't

The more striking figure is not the $10.8 billion on Polymarket's international exchange; it is where $571 million of it came from.

According to onchain analysis firm Allium, U.S.-linked wallets traded $571 million on Polymarket's political markets over the past year, more than any other country, ahead of Hong Kong's $422 million. This requires some explanation, because Polymarket's relationship with American users in 2026 is no longer a simple ban.

Polymarket was fined $1.4 million by the CFTC in 2022 for operating unregistered event-based derivatives and agreed to stop serving U.S. customers at the time, though U.S.-based users were able to access the platform using virtual private networks. Then in late 2025 it came back. The company acquired a CFTC-licensed exchange for $112 million, received an Amended Order of Designation from the regulator in November, and launched a U.S. iOS app in December. The waitlist was removed in May 2026. Americans can now use Polymarket legally.

Sharp international books like Pinnacle serve as pricing benchmarks for the entire ecosystem. The near-identical World Cup winner odds across Kalshi, Polymarket and the major sportsbooks reflected efficient arbitrage between platforms, with sharp money moving to close gaps as they opened. Prediction markets, long criticized for thin liquidity, now hold enough volume that experienced traders recognize the prices as credible.

The more telling data point may be the direction of user flow. Apptopia found that sportsbook users increasingly sampled Kalshi during the tournament, while the share of Kalshi users opening sportsbook apps declined. The theory that prediction markets would be a feeder for traditional sports betting has not held. Kalshi users appear to be staying.