Prediction markets’ biggest month yet, in 3 charts
a16z crypto’s latest report examines October’s activity across prediction markets, showing record trading volume and user traffic. The data suggests the sector is maturing into a media‑like platform.
Key points
- October’s notional volume hit $123.6 B, 1.5× the combined total of 2024‑25 so far.
- Cash actually paid for contracts rose 25% to $22.7 B, outpacing all of 2025.
- Kalshi and Polymarket logged 28 M and 38 M site visits, matching Bloomberg’s traffic.
- All major prediction‑market metrics reached all‑time highs in the month.
- The surge reflects growing user interest, but the market remains volatile and data sources are third‑party.
- Notional volume
- $123.6B
- Combined 2024‑25 volume
- $82B
- Cash paid
- $22.7B
- Kalshi visits
- 28M
- Polymarket visits
- 38M
- Bloomberg visits
- 38M
- Kalshi28 M
- Polymarket38 M
- Bloomberg38 M
- Politico32 M
Record‑breaking October
The a16z crypto brief asks whether prediction markets are entering a growth phase beyond niche speculation. By focusing on October’s activity, the report contrasts two ways of measuring market size: notional trading volume and the cash actually paid for contracts. Using data from platform dashboards and third‑party analytics, the authors chart a sharp uptick across both dimensions.
Volume and cash flow
According to a16z crypto, the total notional volume for all prediction‑market platforms reached $123.6 B in October. That figure is roughly 1.5 times the combined volume recorded for the entire years of 2024 and 2025 to date, which stood at $82 B. Even a more conservative metric—cash paid by buyers, which excludes the $1 payout on each contract—rose 25% to $22.7 B, still eclipsing the cash flow for the whole of 2025. These numbers suggest that participants are committing substantially more capital, not just betting on larger notional positions.
Media‑style engagement
The report also treats prediction markets as media properties. Site‑traffic data from Similarweb shows Kalshi and Polymarket attracting 28 M and 38 M visits respectively in October, putting them on par with Bloomberg’s 38 M visits and only slightly behind Politico’s 32 M. This level of audience engagement indicates that these platforms are becoming information hubs where users both consume and act on real‑world events.
Caveats and data limits
a16z crypto notes that the figures rely on third‑party sources and have not been independently verified. The cash‑paid metric excludes the $1 payout per contract, which may understate the economic impact of larger bets. Moreover, the rapid growth could be driven by short‑term hype around specific events, and past performance is not a reliable predictor of future activity.
Implications for the crypto community
If prediction markets continue to draw both capital and attention, they could evolve into a mainstream conduit for price discovery and public‑interest forecasting. For developers and investors, the data signals a fertile environment for building ancillary services—such as data feeds, analytics tools, and user‑experience layers. However, participants should remain mindful of volatility, regulatory uncertainty, and the nascent nature of the underlying infrastructure.