Prediction markets are becoming real market infrastructure

Kalshi and Polymarket handled a combined $44.8 billion of June volume, up 75 per cent from May, and the more important signal was not the World Cup frenzy itself. It was the way Kalshi and Polymarket kept pulling that retail attention toward contracts on inflation, politics and company events, categories that look less like novelty wagers and more like an early expectations market.

That shift is what turns June’s headline from a culture story into a market-structure story. Sports flow can inflate volumes for a month. What matters now is whether users stay for macro and event contracts, whether liquidity gets deeper rather than merely louder, and whether compliance teams and regulators decide these venues belong closer to exchange plumbing than to gambling apps.

But the same surge that excites market optimists also hardens the counterargument from regulators. A business that suddenly forces banks to rewrite employee rules, campaign staffers to second-guess what they can trade, and courts to revisit the boundary between derivatives law and state gambling enforcement is no longer operating at the fringe.

Why June looked different

June was not just a bigger version of May. The Block’s data showed Kalshi at $31.5 billion of monthly volume, up 87.4 per cent from May, while Polymarket’s offshore venue reached $10.26 billion and Polymarket US added $3.04 billion. A single tournament can create a burst of speculative traffic, but the more durable clue is that the same interface is now training users to price consumer inflation, election probabilities and company-specific outcomes in one place.

Durability still needs proof. Record turnover is not the same thing as exchange-like liquidity, and June may yet prove to be a World Cup peak rather than a new baseline. Even so, the category is starting to acquire signals traditional venues recognize: Polymarket’s first block trade gave larger participants a way to move size without leaning on the public book, while Wintermute’s expansion into prediction-market infrastructure suggested crypto-native market makers see a business worth wiring up.

Just as important, the contracts are creeping into macro narration. CNBC’s report on June inflation expectations treated Kalshi pricing as a live read on whether disinflation had peaked. That is a quiet but meaningful promotion. Once prediction prices start appearing beside Treasury yields, survey gauges and analyst notes, the platforms are no longer selling only spectacle; they are selling a real-time expectations feed.

Polymarket knows that the pitch has to change as it chases a durable U.S. business. Dan Lee, the platform’s head of U.S. operations, framed the domestic relaunch as a credibility exercise in a Fast Company interview.

Trust is the product we are building here.

— Dan Lee, head of U.S. operations at Polymarket, Fast Company

That sounds like branding, but the product roadmap points the same way. Polymarket’s filing to offer regulated margin trading in the U.S. and the earlier push into block activity are features platforms add when they want to be compared with broker venues, not sportsbook apps. Margin does not prove institutional adoption on its own, yet it shows where management thinks the ceiling lies: deeper wallets, larger tickets and repeat use outside tournament calendars.

The compliance ceiling is moving up with the volume

Compliance teams are already treating the category as if it has crossed into finance. Goldman Sachs barred staff from some prediction-market contracts and CNBC reported similar concern spreading across firms, because employee knowledge can map directly onto company-linked or market-sensitive outcomes. That is the user-affected perspective in one move: once a contract references confidential information, the wager stops looking harmless to employers.

Policy alone will not be enough. NPR reported that Kalshi had blocked “dozens” of trades from campaign insiders, yet some attempts still slipped through, a reminder that monitoring has to do as much work as employee handbooks. Traditional markets assume surveillance is continuous because the temptation to monetize material nonpublic information never disappears. Prediction venues are discovering the same rule.

Kalshi’s legal team is openly arguing that the platforms must write parts of that rulebook themselves. Robert DeNault, Kalshi’s head of enforcement and legal counsel, put it plainly in an NPR interview.

It is up to us to make rules of the road for our platform, whether Congress does or not.

— Robert DeNault, head of enforcement and legal counsel at Kalshi, NPR

That confidence may be necessary, but it also exposes the regulatory gap. A federal judge’s refusal to block New York gambling enforcement against Kalshi showed the Commodity Exchange Act does not end the jurisdiction fight by itself. Earlier this year, Minnesota moved to ban prediction markets, and Spain opened an investigation into Polymarket and Kalshi, showing the same business model can be treated as exchange innovation in one venue and prohibited wagering in another.

That is why the next debate is likely to be about market design, not just category labels. The deeper these books become, the more attractive they are to informed traders; the more specific the contracts become, the closer they get to the fact patterns that securities and derivatives compliance teams already know. A contract on an inflation print or a merger outcome may sit outside a stock exchange, but the incentive structure around privileged information is starting to look familiar.

June’s $44.8 billion does not settle whether prediction markets deserve exchange status, and it does not prove sports-driven traffic will survive once the tournament calendar cools. It does settle something smaller but important: the category is now large enough to force responses from market makers, banks, courts and policymakers. Novelty products do not make Goldman rewrite trading rules. Infrastructure-adjacent products do.

If July and August show that macro, political and company-event contracts can hold attention after the World Cup glow fades, Kalshi and Polymarket will have made a stronger case than any trust campaign could. They will have shown that retail traders want a venue for pricing discrete probabilities in real time, and that one of the next market-structure fights may arrive wearing the clothes of a bet.