With the November midterm election less than eleven weeks away, the associated betting markets have already surpassed the total volume of the entire 2024 congressional cycle.
By August 10, traders had placed at least $133 million across markets tied to House and Senate races, significantly exceeding the $92.4 million recorded during the entirety of 2024. The market menu has expanded dramatically, growing from 464 comparable congressional markets in 2024 to 7,466 today. This expansive suite now covers primaries, vote shares, voter turnout, endorsements, candidate remarks, and race winners.
While these headline figures suggest a massive, booming market, deeper participation data reveals a much narrower picture. On Polymarket Global, the top 1% of wallets account for 68% of congressional trading volume. Just ten wallets contribute 17% of that volume, having traded contracts affecting 426 of the 470 seats on the ballot.
Prediction markets are increasingly becoming an integral tool for interpreting elections before a single ballot is cast. Campaigns, donors, and media outlets alike rely on these platforms to gauge public sentiment. However, this emerging role is being shaped by a small pool of capital that continues to set much of the displayed probability, even as regulatory enforcement expands incrementally.
The risks of this dynamic are readily apparent. While a concentrated market can occasionally produce an accurate price, it also risks generating figures that masquerade as broad public consensus, even when the underlying numbers are supported by very few participants.
The Market Count Expanded Faster Than the Audience
The Anti-Corruption Data Collective (ACDC) analyzed 7,466 markets across Kalshi, Polymarket, and Polymarket US, using data current through August 10. Its comparison with the 2024 cycle reveals rapid expansion across almost every metric:
| Congressional Betting Measure | 2024 Cycle | 2026 (As of Aug. 10) |
|---|---|---|
| Total Volume | $92.4 million | $133 million |
| Comparable Markets | 464 | 7,466 |
| Time Left Before Election Day | Complete | Nearly three months |
| Projected Full-Cycle Volume | Actual: $92.4 million | $1.4 billion to $1.6 billion (conditional) |
The upper projection of $1.6 billion is conditional on historical trends. At the same point in the 2024 cycle, only 8% of the final volume had arrived. If 2026 experiences a similar late-stage acceleration, ACDC projects total volume could reach between $1.4 billion and $1.6 billion. The research dashboard will continue to update as the November election approaches.
However, it appears that market breadth has outpaced audience depth. State-level volume is heavily concentrated, with Senate contracts in Texas, Maine, and Michigan, alongside Kentucky’s 4th Congressional District, accounting for 67% of the total. Furthermore, 80% of Polymarket’s congressional markets have fewer than 100 participating wallets. Only ten markets have crossed the 1,000-wallet threshold—a figure roughly comparable to the respondent count in many traditional political polls.
Across 39,820 Polymarket wallets, 87% of markets either have volumes below $10,000 or have high volume concentrated among very few traders. In such thin contracts, a single well-funded order can shift the displayed probability, even if nothing substantive has changed in the underlying race.
The shift from a single headline contest to thousands of granular contracts only compounds this issue. While a national presidential market can attract deep liquidity and constant arbitrage, contracts on House primaries, endorsements, or specific phrases in speeches may appeal to a small, inscrutable group of traders whose information and motives are difficult for outsiders to evaluate.
A Price and a Poll Measure Different Things
A public opinion poll attempts to estimate the views of an entire population. Researchers sample respondents, apply weights to the sample, and publish a margin of error. In contrast, a prediction market simply identifies the price at which traders are willing to exchange a contract that pays out $1 if a specific event occurs.
While that price carries information about probability, incentives, and available capital, dollars directly weight influence. A trader with $100,000 can move the market far more than one with $10. Additionally, individuals can trade repeatedly, hedge across various races, or provide liquidity without necessarily expressing a sincere political belief.
These mechanics can still produce valuable prices. Financial stakes can force participants to defend their positions, and an incorrect price creates opportunities for better-informed traders to step in. Concentrated specialists can indeed outperform a large, uninformed crowd. However, the 68% concentration figure alone cannot prove that the 2026 odds are incorrect or manipulated.
Ultimately, the concentration data defines what these numbers actually represent. The market price is simply the clearing level produced by its current traders, subject to the platform’s specific liquidity and participation constraints. A representative measure of voting intention, on the other hand, must come from a different methodology.
This distinction grows increasingly consequential as market prices leave the trading venue and enter the public sphere. Television graphics, campaign posts, and social media feeds transform these contracts into public probabilities. Donors may use these figures to assess a candidate’s viability, journalists may use them as a live counterweight to traditional polls, and candidates can cite favorable odds as proof of momentum.
This feedback loop operates in both directions. Traders price politics, media outlets distribute those prices, and political actors react to the coverage. In turn, these reactions provide traders with new information to price. In this way, prediction markets become an active part of the election’s information ecosystem.
CryptoSlate has tracked how platforms like Polymarket and Kalshi are increasingly valued as commercial probability feeds with significant media and financial applications. The outlet has also covered proposals to integrate event-market exposure directly into retail brokerage products. Each new distribution channel lends greater authority to these numbers, even when the underlying contract remains extremely thin.
The CFTC Is Moving from Cases to Contract Rules
Election outcomes decided by millions of public ballots present lower direct insider risk compared to events decided within a campaign office. However, the rapidly expanding contract menu includes both types of markets.
The CFTC’s February advisory detailed two specific Kalshi cases. In one instance, a political candidate traded on his own candidacy. In another, a YouTube editor traded on advance knowledge of unpublished videos. The CFTC stated that the misuse of confidential information, fraud, manipulation, and other prohibited practices on designated contract markets fall squarely within its enforcement authority.
Kalshi reported opening 200 investigations over the preceding year, with more than a dozen active cases as of February. The exchange froze the two accounts, imposed financial penalties, and suspended the involved traders. While these actions demonstrate a functioning surveillance program, they also highlight how labor-intensive policing thousands of individual contracts can become.
Polymarket presents a separate enforcement challenge due to its global venue and pseudonymous wallets. While public transactions make unusual success visible, a wallet address alone rarely identifies a campaign employee, pollster, or government official. Establishing the actual person, their official duties, and the source of their information requires far more than simple on-chain monitoring.
An earlier ACDC study of settled Polymarket political markets found the highest warning indicators in outcomes controlled by small groups, particularly military and defense decisions. The study defined a “longshot” as a trade of at least $2,500 at 35 cents or less. Fifty-two percent of qualifying military and defense longshots landed on the winning outcome, compared with 14% across all other categories.
On August 20, ACDC extended that research across 78,496 longshot bets from 12,355 wallets. The analysis identified 152 highly specialized wallets active in military markets that had won over $8 million. These wallets won at least 75% of their longshot bets, earning an average return of 132%—compared to losses of 2% for high-volume traders and 1% for semi-automated accounts. More than half of these specialized wallets placed their first longshot within two days of account creation.
While this wallet pattern does not establish who placed the trades or prove the use of classified information, it does narrow the enforcement landscape. A pseudonymous market can make an unusual trade public in real time while keeping the trader’s identity hidden behind an exchange, routing wallet, or pooled account.
The same research found that public-outcome markets, such as general elections, sit at the low end of insider-risk measures. This distinction is crucial: a bet on who wins a statewide vote is fundamentally different from a bet on whether a candidate drops out next week, secures an endorsement, or uses a specific phrase. The latter category can be settled by decisions known to a small circle of insiders long before the public becomes aware.
The CFTC has now established a rulemaking path to address this distinction. In August remarks, Chair Michael Selig stated that the Commission expects to propose amendments to Parts 38 and 40 of its regulations. These amendments would cover event-contract listing rules, consumer protection, product governance, market design, and incentive programs.
Selig also defended the agency’s exclusive federal jurisdiction over designated contract markets, as well as its proposal to define the public-interest criteria applied to war, terrorism, assassination, gaming, and illegal-activity contracts.
These proposed rules could provide regulated exchanges with clearer duties regarding contract design and retail safeguards. However, they will not make a market with 68% concentration representative, nor will they identify the individuals behind global Polymarket wallets. Platforms will still be tasked with monitoring thousands of thin contracts and explaining why users should trust a probability heavily shaped by just a few accounts.
By Election Day, the market may reach $1.6 billion or fall below the ACDC’s projected range. Either outcome will leave the core issue intact. Election betting already possesses sufficient scale to influence the public conversation, yet its visible dollar volume overstates the actual number of participants creating these odds. The upcoming midterms will test whether prediction markets can earn authority as a credible source of political information before their participation and oversight mechanisms actually match that role.