Betting on November's U.S. midterm elections has already hit $133 million, surpassing the $92.4 million wagered during the 2024 congressional election cycle, the Anti-Corruption Data Collective said on Monday.
The non-profit research and advocacy group forecast that total wagers on the 2026 midterms could reach $1.6 billion if betting activity accelerates at the same pace as it did in 2024.
The breakneck growth has been accompanied by increasing regulatory scrutiny, with critics arguing that the platforms amount to gambling.
The prediction market companies, as well as the Trump administration, have said they are financial markets, not gambling platforms, and that their contracts allow users to hedge against risks or trade on their views of future events.
ACDC said it examined 7,466 markets related to the 2026 U.S. House and Senate races across three platforms, Kalshi, Polymarket and Polymarket US, using data through August 10, and found that the major platforms have opened 16 times as many markets on the midterms compared to 2024.
"Coverage has exploded compared to 2024. There are now multiple markets open for nearly every seat in the country," Michelle Kendler-Kretsch, research fellow at ACDC, said in a statement.
Polymarket and Kalshi did not immediately respond to Reuters' request for comment on ACDC's analysis.
The findings come roughly three months before midterm elections that will decide control of the U.S. Congress. Primary elections across most states are set to run until mid-September, and the midterm election is on November 3.
ACDC data showed that the top 1% of digital wallets on Polymarket Global account for 68% of all trading volumes on 2026 congressional markets.
"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," said David Szakonyi, co-founder and director at ACDC, in a statement.
In 2024, Kalshi won a landmark legal challenge against the U.S. Commodity Futures Trading Commission that cleared the way for Americans to use derivatives to bet on events such as U.S. election outcomes.
