TOTAL VOLUME:
$154.5b
24H VOL:
$271,200,656
24H TRANSACTIONS:
2,984,640,614
OPEN INTEREST:
$1,922,627,141
420,368
Markets across
40,352
events
MATCHED EVENTS:
4,484
PLATFORM COVERAGE:
5
Polymarket:
37%
VS.
Kalshi:
63%
Closed: Oct 27, 12:35 AM EST
Polymarket
Description
The 2026 midterm elections are scheduled to be held on November 3, 2026, with congressional primaries running from March through September. This market will resolve according to the number of Democratic House incumbents who do not win their nominating election to move on to the general election as a result of the 2026 midterm primary elections. An incumbent will be considered not to have won their election if they are not declared the winner of the election they sought, including if they withdraw, suspend, or otherwise leave the race at any point after officially registering as a candidate, regardless of the reason. Incumbents who do not officially register as candidates for reelection will not be considered. This market will resolve based on the results of all House nominating elections, including party primaries, top-two or jungle primaries, and primaries for special elections, that are scheduled to occur between March 1 and September 30, 2026. If a required runoff for any such election or a subsequent qualifying round in a non-partisan primary system could change the market’s outcome, the market will remain open until that contest is conclusively called by this market’s resolution sources. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time of their nominating election. Members of the House of Representatives who are "delegates” or “resident commissioners” not chosen by the people of a state are not included for purposes of resolving this market. The resolution source for this market will be the Associated Press, Fox News, and NBC. This market will resolve once all three sources have conclusively called all relevant nominating elections. If all three sources do not achieve consensus in calling the relevant races for this market, it will resolve based on official state certification of the nominating election results.
Polymarket
The 2026 midterm elections are scheduled to be held on November 3, 2026, with congressional primaries running from March through September. This market will resolve according to the number of Democratic House incumbents who do not win their nominating election to move on to the general election as a result of the 2026 midterm primary elections. An incumbent will be considered not to have won their election if they are not declared the winner of the election they sought, including if they withdraw, suspend, or otherwise leave the race at any point after officially registering as a candidate, regardless of the reason. Incumbents who do not officially register as candidates for reelection will not be considered. This market will resolve based on the results of all House nominating elections, including party primaries, top-two or jungle primaries, and primaries for special elections, that are scheduled to occur between March 1 and September 30, 2026. If a required runoff for any such election or a subsequent qualifying round in a non-partisan primary system could change the market’s outcome, the market will remain open until that contest is conclusively called by this market’s resolution sources. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time of their nominating election. Members of the House of Representatives who are "delegates” or “resident commissioners” not chosen by the people of a state are not included for purposes of resolving this market. The resolution source for this market will be the Associated Press, Fox News, and NBC. This market will resolve once all three sources have conclusively called all relevant nominating elections. If all three sources do not achieve consensus in calling the relevant races for this market, it will resolve based on official state certification of the nominating election results.
Frequently asked questions
Prediction market odds and polling averages often diverge because they measure different things. Polls capture voter preference at a single moment, while this market reflects traders' probabilistic estimates incorporating polls, fundraising data, endorsements, and historical primary patterns. Markets tend to be forward-looking and self-correcting as new information emerges. Traders with strong conviction and accurate track records can move prices away from headline poll numbers. Over time, prediction markets have shown competitive accuracy against traditional polling, particularly when aggregating diverse trader perspectives on complex political outcomes like primary upsets.
On Polymarket, this market is priced through an automated market maker that converts trader buy and sell orders into real-time odds. On Polymarket, prices reflect that venue's order book, liquidity, and how traders price the outcome right now. Each outcome—ranging from the number of Democratic House incumbents failing to win their primary—has its own contract price between 0 and 1, where higher prices reflect stronger trader conviction. As traders buy or sell contracts, the price adjusts continuously. The spread between bid and ask prices tightens with higher volume, making it cheaper to enter or exit positions during active trading periods.
Several catalysts can shift this market significantly. Announced retirements reduce the pool of incumbents facing primary risk, while surprise primary challengers with strong fundraising or endorsements increase upset likelihood. Polling showing incumbent weakness in their districts typically moves prices upward. Major national political events—leadership changes, scandal, or shifts in party momentum—can alter trader expectations about primary competitiveness. Filing deadlines, debate performances, and late-breaking candidate news also drive trading. As primary election dates approach, actual results from early contests provide concrete data that recalibrates odds for remaining races.
