Prediction Markets Hit $113.8 Billion in Q2 as Kalshi Grabs 58.9% Share

Prediction markets had a massive quarter. Notional volume hit $113.8 billion in Q2 2026, up 48.7% from Q1. June alone set a monthly record at $50.7 billion — basically double the $27.5 billion average seen across the five months before it.

Sports drove most of that. The UEFA Champions League Final, Stanley Cup, NBA Finals, FIFA World Cup, and Wimbledon all landed in the quarter, and traders piled in. On Polymarket, sports contracts made up 81% of June volume. Back in January, that figure was 40%. So the shift toward event-driven trading is real and pretty fast-moving. But even as sports traffic surged on Polymarket, the platform’s overall market share actually slipped — from 35.8% down to 30.2% over the quarter. Not a collapse, but not growth either.

Kalshi went the other way.

Kalshi’s Climb and a New Entrant’s Fast Start

Kalshi pushed its market share from 42.4% to nearly 58.9% in a single quarter. That’s a dominant position, and it didn’t happen by accident. While Polymarket was pulling in sports bettors, Kalshi was apparently winning the broader platform battle — holding traders across more contract types and keeping them there. The gap between the two platforms is now wide. Kalshi’s probably the clearest winner of Q2, at least by market share.

Then there’s Rothera. Launched in May as a joint venture between Robinhood and Susquehanna International Group, it came out of nowhere and landed fourth place in June with $2.1 billion in notional volume. That’s a fast start by any measure. The Robinhood name brings retail reach; Susquehanna brings serious market-making muscle. Whether Rothera can hold that position as the quarter’s sports calendar fades is unclear, but the debut was hard to ignore.

It’s worth stepping back here. Two months in, a brand-new platform from a brokerage and a quant trading firm already cleared $2 billion in monthly volume. That kind of number would’ve seemed wild in prediction markets even two years ago. Things shift fast.

Wall Street and Silicon Valley Both Want In

Cboe Global Markets launched Cboe Predicts, a platform offering binary option contracts tied to the Mini-S&P 500 Index. The contracts trade under the symbols XSPBW and XSPBX, and they’re currently available through Interactive Brokers. Charles Schwab is expected to follow. Cboe wants more brokerage firms to pick these up over time, though no specific timeline was given for that broader rollout.

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It’s a different kind of prediction market play. Rather than sports outcomes or political events, Cboe is letting traders bet on market movements through a familiar financial wrapper — binary options on an index. That’s a product traders already understand, tied to infrastructure they already use. The intent seems to be pulling mainstream investors into prediction-style trading without asking them to open accounts on newer platforms they’ve never heard of.

And then there’s Meta.

The company is building a standalone prediction markets app called Arena. Per the source, it’s a priority for CEO Mark Zuckerberg. The app would let users predict real-world outcomes using a points system, not cash — at least at first. But the door is open. Arena could eventually shift into real-money betting, though no timeline or specifics were shared on what that would take.

Meta tried something like this before. Its Forecast app launched during the COVID-19 pandemic and was shut down in 2022. Arena seems like a second attempt, with more executive attention behind it this time. Whether points-based forecasting can build the kind of user habit that survives long enough to become a real-money product — that’s probably the key question. No details yet on a launch date or which markets Arena would cover first.

What the Numbers Actually Mean

The $113.8 billion quarterly figure sounds enormous, and it is by prediction market standards. But it’s worth being clear about what “notional volume” means here: it’s the total value of contracts traded, not money at risk or money won or lost. Still, the growth rate is hard to dismiss. A 48.7% jump quarter-over-quarter isn’t noise. And June’s $50.7 billion in a single month — nearly doubling the prior average — suggests the sports calendar had a real multiplier effect.

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The question now is what happens in quarters without a World Cup. Sports accounted for 81% of Polymarket’s June volume. When the big events dry up, does that volume hold, rotate into other contract types, or just disappear? Polymarket’s market share drop despite the sports surge is a little puzzling on the surface. More volume, less share — which means competitors grew faster. Kalshi clearly did.

The entry of Cboe, Meta, and the Robinhood-Susquehanna joint venture all in the same quarter isn’t coincidence. It’s probably a sign that the sector crossed some credibility threshold — big enough to justify real investment, regulated enough (or becoming regulated enough) to attract institutional names. Cboe in particular is a serious exchange operator, not a startup. Its involvement changes the conversation about where prediction markets sit relative to traditional finance.

Rothera closed June with $2.1 billion in notional volume.