A Handful of Bettors Are Setting the Odds on the 2026 Midterms, New Analysis Finds
Just 1% of wallets control 68% of the midterm betting on Polymarket
Betting on the 2026 midterm elections has already surpassed the 2024 congressional elections, but new analysis from non-profit research and advocacy group the Anti-Corruption Data Collective (ACDC) finds that the odds are being set by a remarkably small pool of bettors.
ACDC examined 7,466 markets related to the 2026 U.S. House and Senate races across three platforms — Kalshi, Polymarket and Polymarket US — with data current up to August 10, 2026.
The group found that $133 million has already been bet on November congressional races with three months until Election Day, surpassing the $92.4 million wagered across the entire 2024 cycle. If betting activity accelerates the way it did in 2024 — when just 8% of total volume had been placed at this point in the cycle — total wagers on the 2026 midterms could reach $1.6 billion. ACDC’s analysis uses market-level data to align the different methodologies used by the platforms to arrive at their reported totals.
The major platforms have opened 16 times as many markets on the midterms as they did in 2024. Compared to 2024, there are more than three times as many markets per House seat, and more than eight times as many markets per Senate seat. An increase in more niche markets on primaries, turnout, vote-share and speeches and endorsements have driven the increase in markets thus far.
But the explosive growth in betting volume and market coverage is masking a deeper problem: the money, and therefore the odds, are controlled by a tiny fraction of participants.
● Marquee contests in Texas, Maine, Michigan and Kentucky’s 4th district alone account for 67% of all state-level betting volume, while the majority of the thousands of other open markets remain thin and largely untraded.
● The top 1% of digital wallets on Polymarket Global account for 68% of all trading volume on 2026 congressional markets.
● Just 10 wallets alone are responsible for 17% of total volume and have placed bets in 426 of the 470 seats up for election — touching 91% of every race on the ballot.
● 87% of markets are either low-volume (under $10,000 wagered) or high-volume but held by very few traders. These two conditions create susceptibility to manipulation, where a small influx of new money can swing the displayed odds.
● Only 39,820 Polymarket wallets have bet on 2026 congressional races. Eighty percent of the markets on Polymarket have fewer than 100 wallets participating, and only 10 markets in the entire cycle have reached 1,000 participants, roughly the number in most political polls.
ACDC warns political analysts, campaigns, media outlets and donors that prediction market prices are still an untested proxy for public opinion. Unlike a scientifically weighted poll of a representative sample, ACDC notes, a prediction market’s price can reflect the conviction — or the manipulation — of a small number of well-funded traders.
Michelle Kendler-Kretsch, Research Fellow, Anti-Corruption Data Collective, said:
“At this point in the cycle, a couple of different things stand out in the data. First, coverage has exploded compared to 2024. There are now multiple markets open for nearly every seat in the country. But, even though the overall volume is higher than in 2024, the trading volume has not kept pace with the breadth of markets available. Four out of every five markets have fewer than 100 wallets betting in them, and the top 1% of traders are responsible for most of the volume. That combination makes prediction markets hard to trust as a real signal.”
David Szakonyi, Co-Founder and -Director, Anti-Corruption Data Collective, said:
“Even though betting volumes are large, electoral prediction markets are highly concentrated among a small number of participants. This poses a number of threats to election integrity. Bettors could deliberately manipulate prices for a given election, offering a form of undeclared and unregulated financial support for a campaign. Markets on outcomes like endorsements and speeches open the door to insider trading. And prediction market odds could undermine trust in elections when the results go a different way.”
Regulatory Background
Under previous leadership, the CFTC attempted to prevent Kalshi from listing markets on the outcomes of political elections, ruling them as “contrary to the public interest.” Kalshi successfully challenged that order in court in 2024. Around the same time, the CFTC issued proposed rulemaking that included event contracts on political elections within a definition of “gaming” and thereby among markets prohibited on regulated platforms. In 2025, the CFTC under new leadership abandoned its appeal of the Kalshi case and withdrew the proposed rule. The CFTC’s June 2026 proposed rulemaking on prediction markets explicitly excludes electoral competitions from its definition of gaming and thereby from markets prohibited under Rule 40.11.
ENDS
NOTES
Download the full briefing: “Gambling on Democracy — Briefing 1: The Midterms on Prediction Markets”
ACDC will continue to update its analysis while diving deeper into election integrity risks related to prediction markets. Visit https://acdatacollective.org/work/gambling-on-democracy for updated data and downloads.
About ACDC
The Anti-Corruption Data Collective (ACDC) leverages public and private data to expose transnational corruption, illicit financial activity and corporate opacity. Our research and investigations seek to document and reduce the harms that corruption causes to human security, democratic participation and environmental sustainability: to people, politics and planet.
Media Contact: team@acdatacollective.org
Gambling on Democracy, Briefing 1: The Midterms on Prediction Markets