TLDR
- Kalshi’s market favorite won 479 of the first 487 midterm races that were decided.
- Kalshi gave Democrats a 93% to 94.5% chance of winning the House on Election Day.
- Election contracts on Kalshi and Polymarket drew more than $3 billion in trading volume.
- Sen. Jeff Merkley and Rep. Maxine Waters are preparing legislative action aimed at prediction markets.
- Senators Elizabeth Warren and John Curtis questioned insider trading controls before the vote.
Prediction markets Kalshi and Polymarket picked the winners in almost every race of the 2026 US midterm elections. Now the party that won both chambers of Congress is preparing to take a closer look at how they operate.
Leading Democrats, including Sen. Jeff Merkley and Rep. Maxine Waters, have criticized the platforms for allowing bets on sensitive subjects. These include elections, war, and terrorism.
As of November 2026, both lawmakers are preparing legislative action aimed at prediction markets. Democrats won majorities in the House and the Senate, which gives them more control over investigations and new rules.
How the Markets Called the Midterms
On Election Day, Kalshi priced the odds of a Democratic House majority between 93% and 94.5%. It placed the odds of a Democratic Senate majority between 73.5% and 76%.
Both outcomes happened. Democrats took control of the House and the Senate, as the market prices suggested.
The record was strong at the level of single races too. According to Kalshi data, the market favorite won 479 of the first 487 races that were decided.
That means favored candidates lost in only 8 of those contests. The hit rate on the early results was above 98%.
Trading activity was high. Election-related contracts on Kalshi and Polymarket drew more than $3 billion in trading volume.
Kalshi alone accounted for more than $2.5 billion of that total. That made it the larger of the two platforms for election trading this cycle.
Why Lawmakers Want Answers
Democratic critics have pointed to three main concerns. They are insider trading, market manipulation, and the gambling-like effect the markets could have on political events.
Insider trading worries center on people with nonpublic information. If such a person can profit from a contract tied to an election, a policy decision, or a military event, the market rewards access instead of insight.
Manipulation is the second concern. Critics fear that prices on high-profile contracts could be pushed up or down, and that those prices could shape how the public views a race.
The third concern is about the bets themselves. Merkley and Waters have objected to wagering on outcomes such as war and terrorism, no matter how well the markets are policed.
Election contracts drove the most volume this cycle and are also the category lawmakers find most troubling. Contracts tied to war and terrorism are a smaller part of the market but sit at the center of the moral argument from Merkley and Waters.
Waters is a senior House Democrat focused on financial services. Lawmakers in that position can push criticism toward formal oversight.
The questions did not start after the vote, and they have not come from one party alone. Before the election, Democratic Sen. Elizabeth Warren and Republican Sen. John Curtis sent bipartisan letters questioning the integrity of election-related contracts.
The senators asked the platforms what measures they had in place to prevent insider trading. Those questions are already on the record as the new Congress takes shape.
In the coming months, attention will turn to whether Merkley or Waters introduces specific legislation and what it targets. Observers are also watching whether congressional committees schedule hearings on prediction markets.
