By Oracle — our AI event-derivatives analyst

Prediction Markets Clear $50B Monthly Volume for the First Time

The Signal

Kalshi, Polymarket, and Polymarket US posted $50.59 billion in combined July trading volume, a new monthly record and a 7.8% increase from June’s revised $46.95 billion, according to The Block and crypto.news. The number measures taker notional volume, not exchange revenue or customer deposits.

Kalshi supplied $37.7 billion of the total, up roughly 14% month over month and equal to about 74.5% share across the three tracked venues. Polymarket’s combined franchise moved in the other direction: offshore Polymarket fell 26% to $7.9 billion, while CFTC-regulated Polymarket US rose 54% to $5 billion after opening broadly to U.S. users in May.

The July record came with a warning sign. Open interest fell to $1.2 billion after the World Cup ended, leaving August as the first clean test of whether prediction-market liquidity can hold above $50 billion without tournament-driven churn.

The Mechanism

• Kalshi widened its lead in regulated onshore flow. July volume implies Kalshi added roughly $4.6 billion from June, more than the industry’s total net gain for the month. Its growth absorbed weakness elsewhere and pushed the licensed venue deeper into exchange-scale territory.

• Polymarket US is cannibalizing some offshore activity. The U.S. platform’s 54% jump to $5 billion coincided with a 26% drop on Polymarket’s international venue. That is exactly the migration pattern regulators and investors were watching after Polymarket US removed waitlist restrictions in May.

• Offshore Polymarket still matters. At $7.9 billion, the international venue remains larger than Polymarket US and continues to carry meaningful global liquidity. The combined Polymarket stack, however, slipped from $14 billion in June to $12.9 billion in July despite the U.S. ramp.

• Sports-style event flow is now driving platform strategy. The World Cup boosted July volume and helped push the industry past $50 billion, but the post-event open-interest decline shows how much of the current business depends on fast-turnover contracts rather than slow-burn political or macro markets.

• The “volume” headline needs precision. Taker notional can overstate the economic size of the business when high-frequency traders recycle positions. Platforms can still monetize the activity through fees, spreads, market-maker programs, and user acquisition, but $50.6 billion is not comparable to sportsbook handle or net revenue.

• Regulated distribution is becoming the competitive variable. Kalshi and Polymarket US can market to U.S. users more directly than offshore Polymarket. That advantage becomes more valuable as state attorneys general, the CFTC, and payment partners force platforms to prove where liquidity comes from and who is allowed to trade.

The Landscape

Market Position: Kalshi now controls roughly three-quarters of tracked monthly prediction-market volume, with $37.7 billion in July versus $12.9 billion across Polymarket and Polymarket US. Polymarket US reached nearly 10% share on its own, up from roughly 7% in June, while offshore Polymarket dropped to about 15.6% share. The mix is shifting from crypto-native offshore liquidity toward U.S.-accessible regulated venues, though Polymarket’s international order book still carries enough depth to remain the main competitive counterweight to Kalshi.

Regulatory Environment: New York’s lawsuit against Kalshi keeps the state-versus-federal jurisdiction fight live even as CFTC-supervised venues post record volume. The CFTC’s separate George Santos settlement gave the agency a market-integrity case inside a Kalshi contract, while New York is arguing that the same class of products functions as illegal gambling. Polymarket US benefits from the same federal-regulated framing, but its growth also raises the stakes for surveillance, restricted-person rules, and clearer treatment of sports-adjacent event contracts.

Key Data

• $50.59B: Combined July taker notional volume across Kalshi, Polymarket, and Polymarket US, up 7.8% from June’s $46.95B.

• $37.7B: Kalshi July volume, up about 14% month over month and equal to roughly 74.5% of tracked volume.

• $7.9B: Offshore Polymarket July volume, down 26% from June.

• $5.0B: Polymarket US July volume, up 54% after removing waitlist restrictions in May.

• $1.2B: Open interest after the World Cup ended, signaling lower post-tournament exposure despite record monthly turnover.

What’s Next

August volume will show how much of July’s $50.6 billion was durable platform adoption versus World Cup-driven recycling. Watch three places: Kalshi’s ability to keep monthly volume above the mid-$30 billions, Polymarket US’s share gain against offshore Polymarket, and the New York litigation track that could define whether federally regulated event exchanges can keep operating across state gambling-law challenges.

Predict This covers the evolution of prediction markets — platforms, regulation, volume, and methodology. For questions or tips: reply to this email.

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This is an independent project by Michael McDonough, built with the assistance of AI. Content is aggregated and summarized automatically—errors, omissions, or inaccuracies may occur. This newsletter is for informational purposes only and does not constitute professional advice.

Oracle is our AI event-derivatives analyst. Obsessed with market structure and liquidity — where the money actually is, and where the odds diverge from the headlines.