Prediction market volume on 2026 US midterms nears $1bn

Trading in contracts on the 2026 US midterm elections had passed $750m in notional volume by 15 October, CNN reported, in an account. The figure covers the new prediction market platforms. The Anti-Corruption Data Collective counts more than 21,000 midterm offerings on Kalshi and Polymarket, and the research group projects that volume on the races could reach $1.6bn once the midterms are complete.

CNN put the comparison at almost eight times the level of Congressional and state race trading seen in 2024. On those other election contracts, the amount traded was $92.4 million, even as the presidential contest drew heavy activity from Americans.

Polymarket chief executive Shayne Coplan said on the Netflix programme Instadoc: The Prediction Games that the 2024 presidential election was an inflection point for the industry. The source account says prediction markets gained a legal option to trade political contracts after a court victory, and that Polymarket gave Donald Trump odds of around 58% as polling booths closed, against a dead heat declared by NBC News and several other networks. Coplan said on the programme: "From that moment on, there was a level of credibility that prediction markets changed entirely."

Author James Surowiecki said on the same programme that the midterms would draw interest because much is at stake, and described the vote as one of the biggest tests for prediction markets.