Kalshi, Polymarket and Robinhood's Rothera took roughly 27% of all legal US sports-betting volume during the tournament, up from about 9% in January, according to H2 Gambling Capital. Kalshi drew more daily app users than either DraftKings or FanDuel.
Kalshi, Polymarket and Robinhood's Rothera took roughly 27% of all legal US sports-betting volume during the tournament, up from about 9% in January, according to H2 Gambling Capital. Kalshi drew more daily app users than either DraftKings or FanDuel.
Prediction markets have moved from the margins of US sports wagering to close to a quarter of it inside a single tournament. According to H2 Gambling Capital, cited by Bloomberg and Fortune, the event-contract platforms Kalshi, Polymarket and Robinhood's Rothera together took roughly 27% of all legal US sports-betting volume during the 2026 World Cup, against about 9% at the start of the year. On that measure, nearly one in three legal sports-betting dollars during the tournament flowed through venues that are not licensed sportsbooks.
The engagement data points the same way. According to Apptopia, an app-analytics firm, Kalshi recorded more daily app users during the tournament than either DraftKings or FanDuel, the two operators that have defined the post-2018 US sports-betting market. That is a striking reversal for platforms that entered the year as challengers to entrenched incumbents.
The installs picture is starker still. Apptopia's data indicates that Kalshi and Polymarket together made up 78.5% of betting-app installs across the six major platforms it tracks through June, up from about 6% a year earlier. A category that accounted for a rounding error of new downloads twelve months ago now dominates them, at least on the platforms in the sample.
The incumbents felt the pull in the opposite direction. Measured from their own tournament peak, DraftKings saw daily active users fall 36% and FanDuel 41%, according to the reporting, with BetMGM and Caesars each down 32%. Those declines are drops from a high-water mark rather than a full-tournament average, and the World Cup is an unusually favourable event for markets offering simple binary outcomes. But the direction is consistent across every operator in the set, and it coincides with the rise in event-contract share rather than running against it.
A Jump From 9% to 27% Is the Fastest Share Shift the US Betting Market Has Seen
The single most consequential figure is the speed of the move. A category tripling its share of a mature, heavily capitalised market in roughly six months is not organic drift; it is a structural repricing of where American bettors choose to transact. The mechanism is straightforward. Event contracts are available in states where sports betting is not licensed, they clear federally rather than state by state, and during a World Cup their binary "who wins" framing maps almost perfectly onto how casual bettors think. The counter-consideration is that a tournament flatters exactly this kind of product, and the 27% figure is an H2 estimate for a peak window, not a durable annual share. Even discounted for both, a jump from 9% to 27% is the fastest share shift the US betting market has seen since legalisation, and it happened without any of the state licences the incumbents spent years and hundreds of millions of dollars acquiring.
The App-Install Data Is the Number That Should Worry the Incumbents
Volume share can spike and recede with a single event, but installs are a forward indicator of the next season's revenue. If Kalshi and Polymarket really are taking 78.5% of new downloads across the tracked platforms, the pipeline of first-time users is tilting decisively away from the licensed sportsbooks, and today's usage gap becomes tomorrow's revenue gap. The incumbents' declines in daily active users, all clustered between 32% and 41%, suggest the displacement is not confined to new customers either. The caveat matters: Apptopia tracks a defined set of six platforms, and installs are not deposits. But acquisition economics are the hardest thing to reverse in this market, and the incumbents have just watched a tournament in which the challengers won the acquisition race outright.
The Displacement Is Real, but the Regulatory Ground Is Still Moving
The strategic complication for the winners is that their share was captured on contested legal ground. The same features that let event contracts reach bettors in every state, federal clearing and a claim to sit outside state gambling law, are precisely what state regulators are challenging, as enforcement actions in New York and elsewhere on the regulatory map make clear. A 27% share built on a legal theory that several states dispute is a powerful commercial position and a fragile one at the same time. The incumbents' most credible route back is not a better product but a favourable ruling.
The tournament has proved that American bettors will follow the simpler, more widely available product wherever it sits. Whether the platforms get to keep the market they have just taken is now a question for the courts, not the app stores.
