Kalshi, the CFTC-regulated prediction market, recorded roughly $9.4 billion in trading volume in June, up sharply from $5.3 billion in May and the highest month in the company's history. Total notional volume topped $31 billion, and daily activity ran above $1 billion for stretches of the month. The driver is not hard to find: the 2026 FIFA World Cup, and the wave of sports speculation it has pulled onto event-contract platforms.
This is the story we flagged when the states began moving against these platforms. Prediction markets are no longer a niche; the World Cup is their coming-out party, and the numbers are the proof. For the full regulatory fight behind the boom, see our explainer on prediction markets versus the states.
The World Cup is the engine
The 2026 tournament was built for this. Hosted across the United States, Canada, and Mexico and expanded to a 48-team, 104-match format, it created far more matches, and far more betting opportunities, than any World Cup before it. The knockout rounds, where a single result ends a run, drew the heaviest action. Canada's Round of 16 tie against Morocco alone generated more than $48 million in volume on Kalshi and another $26.8 million on Polymarket, with US advancement markets adding millions more. Kalshi leaned into the moment, tying up with ADI PredictStreet to push its World Cup presence.
Kalshi is not the only one growing
Polymarket climbed to roughly $4.3 billion in monthly volume over the same stretch, and across the major platforms combined, prediction markets logged an estimated $44.8 billion in total trading activity. Polymarket's month was not all good news: a Wall Street Journal investigation reported that it paid social-media influencers to promote fabricated betting wins through lookalike websites, a reminder that this fast-growing corner of the market is still writing its own rules on advertising and integrity.
One important caveat sits under all of these headline figures. Large volume numbers, especially the "notional" ones, reflect turnover, the total value of contracts changing hands, not new money entering the market. Because traders on an exchange can buy and sell the same position many times before an event settles, a relatively modest amount of real capital can generate a very large volume figure. The growth is real and fast, but the raw dollar totals overstate how much fresh cash is actually in play.
The regulatory shadow over the record
The record month arrives in the middle of an escalating legal fight. CFTC Chair Michael Selig has accused states of pursuing illegal enforcement actions against federally regulated exchanges, arguing that Congress gave his agency sole authority over commodity derivatives markets, prediction markets included. On the other side, casino and tribal gaming groups are lobbying for laws that would pull sports-related contracts under state gambling control, where they would face licensing and gaming taxes like any sportsbook. That question, federal financial instrument or state-regulated bet, is now headed to the courts, and it hangs over every one of these volume records.
Our take
June was the proof-of-concept moment for sports prediction markets. A record set on the back of a World Cup, with eight-figure action on individual knockout ties, is exactly the evidence the industry needed that event contracts can carry mainstream sports betting, and it is why the states are moving so aggressively to tax or ban them. For US bettors, especially in California, Texas, Florida, and Georgia, where there is no legal sportsbook, these platforms are increasingly the only game in town.
We would keep two things in mind. First, read the volume figures with the notional caveat: turnover is not the same as new capital, and headlines that lump the two together make the market look even bigger than it is. Second, the legal ground is genuinely unsettled; access and even the tax treatment of your winnings can shift as the CFTC-versus-states fight plays out. For our part, Kalshi and Polymarket are not among the sportsbooks we partner with or recommend; this is coverage of a market that is now too big to ignore, not an endorsement of it.