Kalshi and Polymarket: $431 Million Traded on US Election Markets
United States.- 4 November 2026 | www.zonadeazar.com Prediction markets linked to the 2026 United States congressional elections have recorded US$431 million in trading volume, according to research published by the Anti-Corruption Data Collective (ACDC).
Released on 2 November, the report examined activity across Kalshi, Polymarket and Polymarket US, identifying substantial growth compared with the 2024 elections alongside potential vulnerabilities involving liquidity, price manipulation and insider trading.
One of the principal findings revealed that 96% of analysed markets with live order books could experience a five-cent price movement through trades worth US$3,500 or less.
Congressional Trading Exceeds $431 Million
The research examined prediction markets associated with elections to the US House of Representatives and Senate.
Using data available through 29 October 2026, the principal figures included:
- Total trading volume: US$431 million.
- Kalshi trading volume: more than US$286 million.
- Congressional markets identified: 28,845.
- Trading volume in 2024: approximately US$124 million.
Overall activity has nearly tripled compared with the previous congressional election cycle.
Kalshi accounted for more than two-thirds of trading volume, significantly exceeding the combined activity of Polymarket and Polymarket US.
Number of Election Markets Increases 61-Fold
Growth was also evident in the number of available contracts.
ACDC identified 28,845 congressional prediction markets, representing 61 times the number recorded in 2024.
On average, the platforms offered:
- 154 markets per Senate seat.
- 46 markets per House seat.
However, the research warned that the expansion in available markets had not been accompanied by proportional growth in liquidity.
Indeed, 90% of markets recorded trading volumes below US$10,000.
This raises questions about market depth and the stability of displayed prices.
66% of Markets Can Be Moved for Under $100
One of the principal concerns identified by ACDC relates to how easily prices could potentially be influenced.
Researchers examined the order books of 15,985 active congressional markets and calculated the amount required to produce a five-cent movement.
The findings included:
- 66% of markets: could be moved by five cents for less than US$100.
- 96% of markets: required US$3,500 or less.
- 90% of congressional races: even the most expensive-to-move market could shift by five cents for less than US$25,000.
The researchers used US$3,500 as a reference because it corresponds to the individual contribution limit for a federal election campaign.
ACDC emphasised that these figures demonstrate potential vulnerabilities and do not establish that actual election manipulation has occurred.
Trading Becomes More Concentrated on Polymarket
The report also examined how activity was distributed among Polymarket participants.
During October, the top 1% of wallets accounted for 75% of congressional trading volume.
Their share had stood at 68% in August.
Researchers identified 89,453 unique wallets across 7,397 congressional markets on the platform.
The concentration of trading is an important consideration when assessing price formation, particularly in markets where relatively few participants can deploy substantial amounts of capital.
Researchers Identify 591 Suspicious Trading Patterns
ACDC identified 591 round-trip transactions involving 544 wallets across 22 Polymarket markets.
These transactions displayed several characteristics:
- Purchases of contracts worth at least US$500.
- Initial contract prices of 95 cents or higher.
- Sales of nearly the entire position within six hours.
- Profits below 1%.
The transactions involved approximately US$618,395 in trading volume, generating a combined profit of just US$34.
According to ACDC, the patterns could be consistent with artificial trading activity or money laundering.
However, the organisation acknowledged that other explanations are possible and that the data alone does not prove unlawful conduct.
$25.5 Million Traded in Insider-Sensitive Markets
Another finding concerned contracts whose outcomes could potentially be known in advance by individuals involved in political campaigns.
ACDC estimated that US$25.5 million had been traded in markets classified as particularly sensitive to insider information.
These included contracts concerning:
- Political endorsements.
- Campaign appearances.
- Candidate statements and mentions.
- Other events potentially known in advance by campaign staff.
The report warned that certain individuals could possess relevant information before it becomes publicly available.
Nevertheless, the trading volume identified does not imply that every transaction involved insider information.
Kalshi Introduces Low-Liquidity Warnings
In response to concerns about transparency, Kalshi has introduced warnings for markets with trading volumes below US$10,000.
The measure aims to inform users when contracts have limited activity.
However, ACDC noted that 90% of the congressional markets examined fell below this threshold.
Michelle Kendler-Kretsch, a research fellow at ACDC, expressed concern about how easily prices could be moved.
She explained that insufficient liquidity can leave markets without enough participants to counter significant trades quickly.
ACDC Calls for Restrictions on Election Betting
The organisation concluded its report by recommending stronger measures concerning contracts linked to democratic processes.
ACDC called on US lawmakers to consider banning election prediction markets.
It also urged platforms to remove certain contracts involving long-shot political candidates.
The recommendations reflect the organisation’s concerns about price manipulation, suspicious trading patterns and unequal access to relevant information.
These proposals form part of the regulatory debate and have not been adopted as binding measures by US authorities.
Industry Impact and Next Steps
The research was published ahead of the 3 November 2026 US congressional elections, amid substantial growth in prediction market activity.
The findings demonstrate a significant increase in trading volume alongside a large number of contracts with limited market depth.
With US$431 million traded, nearly 29,000 congressional markets and 96% of active contracts potentially movable by five cents for US$3,500 or less, ACDC’s report is intensifying discussions about transparency and oversight in political prediction markets.
The findings may contribute to future debates concerning participant protection, market integrity and the regulation of election-related contracts.
Edited by: @fonta
