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Americans have traded more than $750 million on the 2026 midterms, yet the market on which party controls Congress had drawn only $32 million of it when CNN counted. The money is real, but most of it is spread across thousands of markets that are too small to read much into.
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Here is what the new volume figures show, what a watchdog group found when it analysed 21,811 midterm markets, and how to judge whether a price means anything.
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All figures are as reported by the sources named and were current on the dates shown. They have grown since. For live odds, see our 2026 midterm elections predictions hub.
The Headline Numbers
| Measure | Figure | Source and date |
|---|---|---|
| Combined trading on 2026 election markets | More than $750 million | CNN analysis, 24 September |
| Congress control markets (Kalshi and Polymarket) | $32 million | CNN, late September |
| Kalshi Senate control market alone | More than $63 million | Kalshi, 15 October |
| Kalshi Senate, House and governor markets | About $210 million | Kalshi, October |
| Congressional markets counted | 21,811 | ACDC, data through 30 September |
| Projected volume on congressional races | Up to $1.6 billion | ACDC projection for the full cycle |
The $32 million and $63 million figures are not in conflict. They cover different dates, and the $63 million is a single Kalshi market. Volume has grown quickly since September.
What the Watchdog Found
The Anti-Corruption Data Collective, a Washington-based nonprofit, analysed more than 21,000 midterm markets across Kalshi, Polymarket and Polymarket US. It compared them with 463 markets on the 2024 congressional races. Its main findings, as reported:
- Most markets are tiny. 76% hold less than $1,000 in volume.
- A few wallets dominate. Ten wallets control 17% of all congressional volume on Polymarket.
- Small bets can move prices. In thin markets, a modest trade can shift the price a long way.
- The scale is new. The 2024 election saw $92.4 million traded on non-presidential election contracts, against a projected $1.6 billion on congressional races alone this year.
CNN found a similar pattern: many closely watched House battlegrounds had less than $100,000 in volume.
What Kalshi and Polymarket Say
The platforms disagree with the concern. Kalshi’s head of politics growth told CNN that election prediction markets are well calibrated. Both platforms say their markets surface accurate, unbiased information at a time when voters face a lot of misinformation.
Kalshi also says it blocks election trades by politicians and campaign workers, and it has suspended a handful of candidates for betting on their own races. Both sides have a point. Heavily traded control markets may be reliable guides, and thin race-level markets may not be.
Who Is Trading
CNN described the activity as a mix of retail traders having fun, new day traders and large commercial institutions. CNN profiled one trader who says he has made $600,000 across platforms since he started. Kalshi and Polymarket have created markets on nearly every race, and on odd questions such as whether the midterms will “happen on time”.
The broader backdrop is the 2024 election, when about $3.7 billion was traded on Polymarket’s presidential winner market, according to the platform. Politics prediction markets have grown into a mainstream feature of election coverage since.
Prediction Markets Have Gone Mainstream
- On air. CBS News and CNN now use Kalshi data in coverage, and each has a partnership with the platform. Networks are adding prediction market prices to midterm coverage.
- In reference sites. Kalshi has integrated its odds into Ballotpedia.
- In the hands of newcomers. Retail traders now arrive through media and apps, and many lack the tools to judge when a price reflects information and when it reflects thin trading.
Roughly one in five Americans were very or somewhat familiar with prediction markets as of a March poll, so many readers are meeting these prices for the first time.
How to Judge Whether a Market Price Means Anything
| Question | Why it matters |
|---|---|
| How much has traded? | A market with millions traded is harder to move than one with a few thousand dollars |
| How wide is the spread? | A wide gap between buy and sell prices signals thin trading |
| Do other sources agree? | If polls, models and other markets point the same way, the price is more credible |
| Who sells the data? | Platforms earn from trading, so their commentary is a source, not a verdict |
As a rule of thumb, treat the national control markets as the most reliable and a House race with a few thousand dollars traded as little more than a guess.
What It Means for Readers
Heavy volume does not make a market right, and light volume does not make it wrong. It does tell you how much weight a number can bear. If you are following the midterms through prediction market prices, check how much has traded and read the odds alongside polls.
Election betting is prohibited in roughly two dozen states, and a Reuters/Ipsos poll found most Americans oppose it. See our guide to election betting by state before you do anything beyond reading prices.
Frequently Asked Questions
How much has been traded on the midterms?
CNN counted more than $750 million on 2026 election markets on Kalshi and Polymarket as of 24 September. A watchdog projects up to $1.6 billion on congressional races alone over the full cycle.
Which midterm market has the most volume?
The control-of-Congress markets are the largest. Kalshi’s Senate control market alone had more than $63 million traded by 15 October.
Are midterm prediction markets reliable?
Kalshi says election markets are well calibrated. A watchdog says most are too thin to be reliable and that a few wallets account for a large share of volume. Heavily traded markets are more dependable than thin ones.
What is the Anti-Corruption Data Collective?
A Washington-based nonprofit that analysed more than 21,000 midterm markets using data the platforms publish.
How much was traded on the 2024 election?
About $3.7 billion on Polymarket’s presidential winner market, according to the platform.
Is it legal to trade on the midterms?
It depends on your state. About two dozen states prohibit election betting under existing law, and whether those laws apply to prediction markets is being contested.
Prediction markets are not sportsbooks. Event contract trading involves significant risk and is not appropriate for everyone. You can lose your entire stake. Platforms are typically 18+ and are not available in all states, and some states prohibit betting on elections. Volume figures are as reported by the sources named and are not predictions or guarantees. This article is informational and is not financial, legal or voting advice. GamingToday does not endorse any candidate or party. If gambling or trading stops being fun, call 1-800-GAMBLER for confidential support.
