Midterm betting passed $220 million three weeks out. Here is where the money sits, who is placing it, and what 60 percent of Americans think of it.
The numbers, and what changed since 2024
The ACDC study is the first attempt we have seen to count every congressional market on both big platforms rather than quote a headline figure from one of them. It covered 21,000-plus markets on the 2026 midterms on Kalshi, Polymarket's international site and Polymarket US, with volume counted to 30 September, and compared them with 463 markets on the 2024 congressional races. The volume more than doubled; the number of markets grew more than forty-fold. Most of the new markets barely trade.
| Measure | 2024 cycle (full) | 2026 cycle (to 30 Sept) |
|---|---|---|
| Congressional market volume | $92 million | More than $220 million |
| Number of congressional markets | 463 | More than 21,000 |
| Share of markets asking who wins | 71% | 16% |
| Share of markets on winning margin | Not reported | 58% |
| Top 1% of Polymarket wallets, share of volume | Not reported | 70% |
The shift in what the markets ask is the detail worth keeping. In 2024, seven in ten election markets were a plain who-wins question. This cycle only 16 percent are; 58 percent ask about the winning margin, and there are far more turnout markets. That is partly a product decision, since a margin ladder lets a platform list twenty strikes on one race, and partly a sign of who is trading: margin and turnout contracts are harder to price from a poll average and reward people with their own model or their own information.
Where the money sits
Reuters names the Texas Senate race between Democrat James Talarico and Republican Ken Paxton as the single biggest draw, with Maine, Michigan and South Carolina behind it. Kalshi's public midterms page on 14 October gives the shape of the rest. The table below is what it showed; prices are the Yes side in percent and volume is the figure the page displays for the market.
| Kalshi market, 14 October | Price | Volume shown |
|---|---|---|
| Democrats control the Senate | 62% | Not shown |
| Democrats control the House | 90% | Not shown |
| Texas Senate winner | Talarico 63%, Paxton 37% | Not shown |
| Maine Senate winner | Jackson 56%, Collins 44% | Not shown |
| Michigan Senate winner | El-Sayed 68%, Rogers 32% | Not shown |
| Ohio Senate winner | Brown 59%, Husted 41% | Not shown |
| Democratic Senate seats after the midterms | Above 52: 35% | $4.55 million |
| Republican Senate seats after the midterms | 48: 17% | $2.38 million |
| Maine-Texas Senate combo | Talarico and Jackson 47% | $1.66 million |
| "Blue wave this year?" | Yes 78% | $1.44 million |
| Los Angeles mayor winner | Raman 56%, Bass 46% | $102.3 million |
Two things stand out. The largest market on the page by a wide margin is not a congressional race at all but the Los Angeles mayoral contest, at $102 million, which says something about where Kalshi's California user base puts its money. And the seat-count ladders, the combos and the "blue wave" contract together carry more displayed volume than any single Senate race, which is the 58-percent-margin finding showing up in one platform's order book. Note that the Los Angeles market's two sides sum to 102 and the Maine exact-outcome market's to 101; those are bid and ask displays, not a pricing error, and the gap is the spread.
Who is on the other side of the trade
The 70 percent figure is the one the platforms will like least. ACDC found that on Polymarket the top 1 percent of wallets by congressional-market volume account for 70 percent of that volume this cycle. That is consistent with what every exchange looks like once market makers and large accounts arrive, and it does not by itself say anything improper is happening. It does cut against the way election markets are sold to the public. Kalshi's spokesperson told Reuters its data is "bottom-up, not elites-driven" and that prediction markets "are a way to see what people are saying when there's money on the line." If seven dollars in ten come from one wallet in a hundred, the crowd being measured is small.
The integrity question is the other one. NPR reported in May that campaign staffers had bet on races they worked on; Kalshi has since suspended several candidates for trading on their own races and, on 31 August, fined a North Carolina congressional nominee for doing so. Both platforms block trades by politicians and campaign workers and say they refer misconduct to US authorities. Polymarket told Reuters it runs "state-of-the-art surveillance and dedicated detection systems built for political markets" and that its election markets are 98 percent accurate the day before a vote. New York has separately banned state officials from using nonpublic information to profit on prediction markets, and the House Oversight Committee has an open insider-trading inquiry that it widened this month.
What the public thinks, by the numbers
The Reuters/Ipsos poll published on 12 October is the largest we have seen on the question. It surveyed 4,506 US adults between 30 September and 5 October, with a margin of error of 1.5 points, and told respondents that prediction markets let people "wager money on the outcome of real-world events" before asking about elections, military actions, government policy decisions and sports separately.
| Reuters/Ipsos, 30 Sept to 5 Oct 2026 | Result |
|---|---|
| Oppose betting on election results via prediction markets | 60% (13% support, 24% unsure) |
| Oppose, Democrats / Republicans | 69% / 61% |
| Oppose betting on US military actions | 65% |
| Consider prediction-market wagering to be gambling | About three quarters |
| Have used a prediction market to bet money | 7% |
Kalshi called the poll biased and its questions leading, pointing out that it asked about "betting on war" when Kalshi does not list war markets, and said a fairer survey would measure familiarity first. That objection has some force: the poll did not ask whether respondents knew what a prediction market was, and a separate Ipsos poll in March found only 21 percent were very or somewhat familiar with them. Polymarket's response was that more than 90 percent of its visits are to look at prices rather than to trade. Both answers concede the same point in different words: the audience for election odds is much larger than the group placing them, and the group placing them is unpopular with the audience.
The ad money and the media deals
The platforms are spending into that. Ad Age reported on 14 October that Polymarket has hired the film director Kathryn Bigelow for its first US political advertising campaign, a set of cinematic spots that present Polymarket's live prices as an alternative to polling ahead of the midterms; no budget was disclosed. Kalshi's route is through newsrooms rather than commercials. CBS News said on 30 September that it would add real-time Kalshi prices to its midterm coverage alongside its own polling, Kalshi has similar arrangements with CNN and CNBC, and it licenses vote counts and race calls from the Associated Press. CBS and CNN now share an owner after Skydance completed its purchase of Warner Bros. Discovery on 6 October. For a product that 60 percent of the country says it opposes, being the number on the election-night screen is the strongest marketing available, and it costs less than a film director.
The overhang: a rule, a template and a deadline
None of this runs in a settled legal environment. The CFTC published a proposed rule on 9 October that would write event contracts into the Commodity Exchange Act's swap definition, with a 30-day comment window, alongside an interim final rule that wrote state-licensed casino and sportsbook bets out of it. Election contracts are not the target of the state fight, which is about sports, but the Sixth Circuit's 25 September holding that even a contract that is a swap does not displace a state gambling law is the template state attorneys general are now working from, and 39 of them plus the District of Columbia signed the 7 October Supreme Court brief against Kalshi. The platforms' answer to the public, the poll and the states is the volume figure itself. $220 million in three quarters of a midterm year is the argument that the product exists whether or not it is approved of; the 70 percent figure is the reminder that most of that argument is made by very few people.
Method and limits
The $220 million, $92 million, 21,000, 463, 16, 58 and 70 percent figures are from the Anti-Corruption Data Collective analysis as reported by Reuters (Hannah Lang and Michelle Price) on 14 October; we have not seen the underlying dataset, and the analysis counts volume to 30 September, so the cycle total is already higher. Kalshi prices and volumes are what Kalshi's public midterms page displayed on 14 October; prices move and the page shows only part of its 35 Senate markets, so the table is a sample, not a ranking. Volume figures on Kalshi are notional, not money at risk. Poll figures are from Reuters/Ipsos as reported by Fortune on 12 October, including the fielding dates, sample and margin of error; the party breakdown for support and unsure responses was not published. The Polymarket campaign is from Ad Age as reported by Prediction News; we could not retrieve the Ad Age piece directly. CBS, CNN, CNBC and AP arrangements are as described by Fortune. We do not know Polymarket US's own share of the $220 million. Nothing here is legal, financial or betting advice.
Frequently asked questions
How much has been bet on the 2026 midterms on prediction markets?
More than $220 million across Kalshi, Polymarket's international platform and Polymarket US through 30 September 2026, according to an Anti-Corruption Data Collective analysis reported by Reuters on 14 October. The entire 2024 congressional cycle drew $92 million.
Which midterm races attract the most prediction market money?
The Texas Senate race between James Talarico and Ken Paxton draws the most, followed by the Senate races in Maine, Michigan and South Carolina. On Kalshi's midterms page on 14 October the largest single market by volume was the Los Angeles mayoral race at about $102 million, and the Democratic Senate seat-count market had $4.6 million.
What do Americans think about betting on elections?
A Reuters/Ipsos poll of 4,506 adults fielded 30 September to 5 October 2026 found 60 percent oppose using prediction markets to wager on election results, 13 percent support it and 24 percent are unsure. Opposition was 69 percent among Democrats and 61 percent among Republicans. About three quarters called it gambling, and 7 percent said they had used a prediction market.
Who is placing the midterm bets?
On Polymarket, the top 1 percent of wallets by congressional-market volume account for 70 percent of that volume this cycle, per the ACDC analysis. Kalshi says its data is bottom-up; both platforms block trading by politicians and campaign workers and say they refer misconduct to US authorities.
Related
- How do election prediction markets work?
- Is Kalshi legal in your state? The 50-state tracker
- Is Kalshi legal in New York? The $36 billion James lawsuit
- Is Kalshi legal in Texas?
- Odds converter: cents, American odds and implied probability
Sources
- Reuters (Hannah Lang and Michelle Price), Inside the booming market for US midterm election bets, 14 October 2026, via U.S. News, for the ACDC figures and the platform statements.
- Fortune, Election betting: 60% of Americans oppose prediction-market wagers, 12 October 2026, for the Reuters/Ipsos poll detail, the Kalshi and Polymarket responses and the CBS News arrangement.
- Kalshi, 2026 midterm election markets, prices and displayed volumes as shown on 14 October 2026.
- Prediction News, Polymarket hires director Kathryn Bigelow for first US political ad campaign, 14 October 2026, reporting Ad Age.
- The Block, Kalshi CEO defends prediction markets amid insider trading concerns, 14 October 2026, for the New York officials' ban and the insider-trading cases.
- CFTC, Release 9309-26, 9 October 2026, for the proposed and interim final rules.
- BetG8, Prediction market change log, for the 31 August North Carolina fine and the 7 October state brief.
18+ only. This page reports published data, polling and company statements. It is not legal, financial or betting advice. If gambling stops being fun, help is available at 1-800-GAMBLER.