Midterm trading tops $750 million on Kalshi and Polymarket, as a handful of wallets dominate
Trading on 2026 election markets has passed $750 million across Kalshi and Polymarket, across more than 21,000 midterm markets. Congressional betting alone is more than double the whole 2024 cycle. Who is trading, where the money goes and the insider-trading worries.
In this article
The 2026 midterms are the biggest US election yet for prediction markets. More than $750 million has been traded on 2026 election markets across Kalshi and Polymarket, according to a CNN analysis of public data, and the Anti-Corruption Data Collective counts more than 21,000 midterm markets on the two platforms. The election is on 3 November.
The numbers
| Measure | Figure | Source |
|---|---|---|
| All 2026 election markets, Kalshi + Polymarket | More than $750 million | CNN analysis |
| Midterm markets listed | More than 21,000 | Anti-Corruption Data Collective |
| Congressional races, through 30 September | About $221 million | Anti-Corruption Data Collective |
| Congressional races, entire 2024 cycle | About $92.4 million | Anti-Corruption Data Collective |
| Projected congressional total for 2026 | $1.4–1.6 billion | Anti-Corruption Data Collective |
Where the money goes
Some of the biggest election markets are not about Congress at all: by late September, Kalshi's Los Angeles mayor market had drawn about $97 million and its California governor market more than $50 million (LA mayor odds, California governor odds). Chamber control has grown fast in the final weeks; Polymarket's House market alone has passed $19 million (Senate and House control odds). Many competitive House districts, by contrast, have traded less than $100,000, which makes their prices easy to move.
A handful of wallets
The data collective found that the top 1% of Polymarket wallets account for about 70% of congressional betting volume. Concentration matters: when a few traders set the price, a market reflects their views and their bankrolls more than the crowd's.
Insider-trading worries
CNN reported in October that very specific midterm markets, on endorsements, rallies and debate moments, have drawn more than $20 million, and that kind of market is exactly where someone with inside knowledge could profit. Candidates have already been fined for trading on their own races. Kalshi responded this month with new transparency tools, including accuracy scores and low-volume warnings (Kalshi's transparency features).
