Bigger Than the Sportsbooks

Sometime this year, while most of the industry was watching the state-by-state court fights, the prediction market business quietly became bigger than the business it was supposed to be a niche version of. Combined monthly trading volume on Kalshi and Polymarket rose from $26 billion in May to $53 billion in July, according to a Pew Research Center analysis. Americans wagered roughly $14 billion a month at legal sportsbooks in 2025. The upstarts are not catching up anymore. They have lapped the field.

The World Cup made the shift impossible to ignore. Kalshi alone posted $31 billion in notional volume in June, with sports contracts accounting for around 85 percent of its trading, and World Cup markets on the platform passed $22 billion. Polymarket set records on both its international and regulated US exchanges. Robinhood's new venture processed $2 billion in its first month. This is no longer a sideshow for crypto curious traders. It is the fastest growing audience in sports wagering.

The honest footnote

Volume and handle are not the same animal, and any brand planning around these numbers should know the difference. A sportsbook counts a bet once. An exchange counts every trade, and a single contract can change hands many times before it settles. Measured the strictest way, the actual dollars traders paid for contracts on Kalshi and Polymarket US in August came to $13.8 billion against $10.1 billion in online sportsbook handle across 27 reporting states. The crossover survives the correction. The margin is just thinner than the headline suggests.

A different crowd is walking in

The more interesting story for marketers is who is doing the trading. During the World Cup, Kalshi drew a surge of female and first-time bettors who had never touched a traditional sportsbook app. Institutional trading firms are building dedicated desks. And the platforms just put $1.48 billion of midterm election volume through their systems in a single day, a stress test for both their forecasting reputation and their compliance teams.

The establishment has noticed. The NBA named Kalshi and Polymarket its preferred prediction market exchanges in October, signed an integrity agreement with the CFTC, and watched the 76ers become the first team to sign their own deal four days later. When the leagues start selling sponsorship category rights to an industry, that industry has arrived.

What it means for the brands

Here is the tension every operator in this space now faces. The audience is enormous and growing, but it is also new, skeptical and hard to reach. An Ipsos poll earlier this year found only about one in five Americans were familiar with the prediction market platforms, and nearly 40 percent of those who knew them viewed them as bad for society. That is why the marketing has escalated so fast: Polymarket packed a single 60-second ad with LeBron James, Derek Jeter, Eli Manning, Spike Lee and a dozen more faces, and Novig lit up the internet with Sydney Sweeney. They are trying to trade money for trust.

Celebrity reach buys awareness. It does not buy understanding, and understanding is the actual bottleneck. A first-time trader does not need to know who is in the ad. They need to know what a contract is, why the price moves, and why this is not just a sportsbook with a different accent. The brands that win the next two years will be the ones whose creative explains the product as well as it sells it, in a voice a newcomer can trust, across a compliance map that changes by the week.

• Plan for the newcomer, not the sharp. The growth is coming from people who have never placed a traditional bet. Creative that assumes sportsbook fluency will miss them.
• Treat education as a brand asset. Explaining how a market works, clearly and honestly, builds more trust than another odds boost ever will.
• Watch the measurement language. Volume, handle and revenue are different numbers, and audiences, regulators and journalists are learning to tell them apart. Brands should too.
• Build for a moving compliance map. State by state fights are redrawing where sports contracts can be offered, so campaigns need versioning and legal review baked in from the start.

The crossover is real, the crowd is new, and the leagues have picked their partners. The only question left is the one this industry keeps handing to its marketers: now that everyone is watching, what do you actually have to say?