Prediction markets bet on Democratic sweep of House, Senate in midterm elections

As congressional midterms in the United States approach in 2026, prediction markets and polling-based models present differing views on the Democratic Party's prospects. While both methods generally agree that Democrats are likely to retain control of both chambers of Congress, prediction markets exhibit slightly less confidence than polling models.

According to Yahoo Finance's analysis, Democrats have a 94% chance of securing the House of Representatives, compared to a 96.2% probability estimated by polling-based forecasts. Similarly, the prediction markets project an 80.2% likelihood of Democrats taking control of the Senate, whereas polling models estimate an 80.2% chance.

The gap between these two estimates has narrowed as Election Day nears, with the disparity between prediction markets and polling models shrinking from around 7.3 percentage points since September 1 to just 2.9 percentage points on Tuesday morning. As the voting date draws nearer, prediction markets and poll-based forecasts are becoming increasingly aligned.

Analysis performed by Yahoo Finance combines data from three major prediction markets—Kalshi, Polymarket, and PredictIt—and compares it with two polling models: one developed by statistician Nate Silver and another called ElectIt, created by Harvard. The study reveals that the discrepancy between prediction markets and opinion polls has garnered significant attention post the 2024 presidential election, when these markets predicted Donald Trump's victory despite traditional polls suggesting otherwise.

The debate has intensified as prediction market companies like Kalshi and Polymarket argue their forecasts are more accurate due to the financial stakes involved, while also facing criticism over the potential risks of election-related trading, market manipulation, and the impact on public perception. In response to these concerns, Democratic Senator Elizabeth Warren and Republican Senator John Curtis co-authored a letter to Kalshi and Polymarket, questioning the risks associated with these markets.

They highlighted the platforms' growing influence and called for greater oversight. Meanwhile, legal challenges surrounding prediction markets' regulation have emerged, with Utah filing a lawsuit against Kalshi, claiming the state should be allowed to enforce its anti-gambling laws on these platforms.