Kalshi and Polymarket have handled more than $750 million in combined trading on 2026 U.S. election markets, according to CNN, turning the midterms into a major volume cycle for the prediction market industry, per Bonus's coverage of the CNN reporting.
CNN said the most active contracts now span high-profile state and federal races. On Kalshi, the biggest markets included Los Angeles mayor winner at $96.9 million in volume, Florida Republican governor nominee at $71 million, and California governor winner at $52.5 million, per the report. On Polymarket, the most-watched contracts included balance of power in Congress after the midterms at $13.5 million, which party will win the U.S. House at $12.2 million, and which party will win the U.S. Senate at $5 million, per the report.
As of October 1, 2026, both venues are pricing a Democratic Congress, per NextPredict. Polymarket, which recently launched its Midterms Hub, gives Democrats a 93% chance of controlling the House and 63% for the Senate as of October 1, 2026. Kalshi tells much the same story: its Senate contract put Democrats at roughly 64% as of October 1, 2026, while Democrats were priced as 91.6% favorites to take the House, per the same report.
The structure explains why markets are far more confident about the House than the Senate. Republicans hold the Senate 53-47, counting the two independents who caucus with Democrats, so Democrats need a net gain of four seats for outright control, and all 435 House seats are being contested, per NextPredict. Kalshi's 'blue wave' contract, requiring at least 218 Democratic House seats and 49 Senate seats, reached 83% in September, per NextPredict. Kalshi's Senate control market alone had attracted nearly $42.4 million in notional volume as of October 1, 2026.
The scale is already historic. Trading on the 2026 midterms had reached $133 million by August, exceeding the $92.4 million traded on congressional races during 2024, according to the Anti-Corruption Data Collective, per NextPredict.
Media institutions are treating market prices as election infrastructure. CBS News has partnered with Kalshi to integrate its market data into coverage of the 2026 midterm elections, designating Kalshi the network's prediction market sponsor, the arrangement announced on CBS Mornings by Anthony Salvanto, executive director of elections and surveys at CBS News, per SCCG's report of World Casino News. The agreement will incorporate Kalshi forecasts alongside polling, reporting and analysis for congressional control and key races, including contests in Texas and Maine. It follows Kalshi partnerships with CNN in December 2025, a multiyear exclusive with CNBC, and an agreement with The Associated Press in March for official vote counts and race calls, per the report.
Benjamin Freeman, Kalshi's head of politics growth, told CNN that election prediction markets are 'well-calibrated' and can absorb new information faster than polls, per the Bonus report. A Polymarket spokesperson told CNN the platform offers 'transparent, accurate, real-time information' and called it 'an antidote to the disinformation poisoning public dialogue.'
Election officials have raised concerns alongside the volume. Dean Logan, Los Angeles County's top election official, said he wishes election markets 'would go away' and described post-primary disinformation in Los Angeles as 'destructive,' per CNN via Bonus. CNN also reported that the first public political insider-trading cases surfaced in April, when Kalshi fined and suspended three minor candidates for betting on their own races, and that Laurie Buckhout, the Republican nominee in a North Carolina House race, apologized and paid a fine of about $2,600. A separate dispute over Kalshi's settlement of an Alaska top-four Senate primary market raised questions about how clearly election contracts are written and resolved, per the report.