Kalshi and Polymarket Process Billions in Midterm Election Trades as Scrutiny Mounts

Trading on regulated and offshore prediction platforms surged during the midterm elections, processing billions of dollars in volume as participants repriced congressional and state-level races in real time on election night.

Midterm contract volume across exchanges operated by Kalshi and Polymarket more than tripled from the final week of October into election week, according to an analysis by CNBC Business (https://www.cnbc.com/2026/11/09/millions-of-dollars-poured-into-prediction-markets-on-election-night.html) based on tracking data from Predictions.com that excluded combo contracts. Across both platforms, more than 87% of election markets assigned the eventual winner at least a 90% implied probability 24 hours prior to election night, heavily assisted by a slate dominated by noncompetitive races.

The influx of capital underscored the accelerating adoption of event-based derivatives to track civic and political milestones. Yet the trading also illustrated the limits of contract liquidity as an independent forecasting mechanism compared to traditional polling models.

Market prices began shifting toward Democratic candidates before 7 p.m. on Nov. 3 as initial results arrived from Indiana. While broad directional trends tracked incoming tallies, high-conviction trades took heavy losses in key contests. On Kalshi, more than $1 million traded after 8 p.m. on contracts backing the reelection of Texas Gov. Greg Abbott, who went on to lose to Democratic challenger Gina Hinojosa by over 700,000 votes, according to Associated Press tallies. Later in the evening, after 11 p.m., traders directed more than $1.4 million on Kalshi into contracts wagering that Republicans would fail to hold control of the House of Representatives.

Following the vote, Kalshi chief executive Tarek Mansour and Polymarket chief executive Shayne Coplan publicly credited their platforms with accurately anticipating results. However, academic researchers and statistical forecasters disputed claims that the markets outperformed existing predictive tools. Koleman Strumpf, an economics professor at Wake Forest University, told CNBC Business that while prediction markets performed well, they did not beat the best conventional forecast aggregators.

Nate Silver, founder of the Silver Bulletin newsletter and an advisor to Polymarket since 2024, also disputed assertions of market primacy. Silver wrote that prediction market probabilities converged heavily toward statistical forecast models in individual Senate and gubernatorial races rather than generating an independent predictive lead, cautioning that event markets were effectively taking credit for established statistical modeling.

In total, Kalshi reported exceeding $3 billion in cumulative midterm contract volume, a metric that included mayoral contests, while Polymarket reported nearly $700 million across its two exchange operations for midterm-related trades. Despite the political surge, sports-related contracts continue to represent the largest trading category across both venues.

That reliance on sports volume faces emerging legal and regulatory pressure. Three days after the midterms, Sen. Adam Schiff (D-Calif.) criticized the Commodity Futures Trading Commission on X for allowing prediction platforms to list sports contracts nationwide. Schiff argued that permitting such contracts across all 50 states and on Tribal lands violates state gaming statutes and Tribal sovereignty, highlighting the next regulatory battleground as prediction exchanges seek federal legitimacy.