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 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.
But the regulated U.S. app and the global platform are fundamentally different products. The U.S. version requires full KYC identity verification, is funded through registered futures commission merchants rather than crypto wallets and settles in U.S. dollars. The global platform, still geoblocked for U.S. IP addresses, has no identity checks, settles in USDC and carries a far wider range of markets.
The $571 million figure refers to Americans trading on that global platform through VPNs and existing crypto wallets. Allium tracked wallet behavior rather than IP addresses, which is how a VPN that defeats geoblocking still leaves U.S. fingerprints in the data.
Named FIFA's official prediction market partner part-way through the tournament, Kalshi had branding rights, in-venue presence and a media distribution deal with Fox Sports.Though notably, the user growth was already well underway when Kalshi signed its co-branding deal with ADI Predictstreet, the FIFA World Cup’s official prediction market partner, on June 26, just four days before Apptopia data was recorded. Both Kalshi and Polymarket have advertised heavily during games, with ads airing during the halftime break, as well as the so-called hydration breaks during the American broadcasts.
App data from Apptopia found that by June 30, Kalshi's daily active users were 36% above their June 15 level. Over the same period, DraftKings fell 36% from its tournament peak, FanDuel dropped 41% and BetMGM and Caesars each declined 32%. Traditional sportsbook apps spiked early and faded, while prediction markets built steadily throughout.
Kalshi and Polymarket together accounted for 78.5% of betting app installs across the six major platforms tracked by Apptopia through June. A year earlier, the two prediction markets combined for roughly 6% of that same audience.
The demographics were equally surprising. Kalshi's female users grew 106% during the tournament, more than twice the 54% growth rate among male users. Kalshi attributed at least some of this growth to the reality television program Love Island, Barron's reported, but some of the surge was tied to the World Cup. By late June, 33.3% of Kalshi's user base was female, compared with 22 to 23% for DraftKings and FanDuel. It was pulling in people who had never previously touched a betting product.
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