How Polymarket Election Markets Work: 2026 Midterms Guide

Contracts, prices, resolution rules, and how to read a race page, using the midterm markets trading right now

GhostLeg, 2026-08-11, 5 min

Prices in this post are a snapshot from Thursday, August 7 at 12:10 PM ET. Election markets trade around the clock; the live politics board carries the current numbers.

A race becomes a set of contracts

Polymarket turns an election into contracts you can buy and sell. Each contract asks one precise question, pays $1 if the answer resolves yes, and trades in cents until then. When "Democratic Senate control 2026" trades at 45.5 cents, the market is collectively pricing that outcome at roughly a 45.5% probability: buyers at that price make money if it happens, sellers make money if it does not, and the price settles where the two sides balance.

That is the whole core mechanic. Everything else about reading election markets well is detail on top of it: which contracts exist, how multi-candidate races are structured, what exactly makes a contract resolve yes, and how prices behave on the way to November. This guide covers each, using the markets trading right now; GhostLeg currently tracks about 1,060 active Polymarket election contracts (alongside roughly as many on Kalshi) across 87 open race pages.

Candidate markets, party markets, and why the difference matters

Election markets come in two main shapes, and conflating them is the most common reading error.

Party-level contracts ask which party wins a race or a chamber: one contract per party. The headline chamber markets work this way, and their prices read directly as probabilities.

Candidate-level markets list a contract per named candidate, sometimes a dozen or more per race, including candidates who have not entered. Here a party's probability is the sum of its candidates' prices, and reading one candidate's price as the party's chance undercounts it. When GhostLeg computes party-level numbers from candidate markets, we sum same-party candidates; our race pages do this for you.

Multi-candidate races on Polymarket also carry structural bookkeeping (linked no-side contracts that keep the set of outcomes internally consistent), which occasionally leaves dead placeholder contracts visible in raw data. We filter to actively traded contracts; if you read the raw feeds, you should too.

Resolution rules are the fine print that decides everything

A contract's price is an answer to its exact question, and the exact question includes how it settles. Polymarket election contracts typically resolve on a consensus of major network calls or official certification. Kalshi, the other major venue, generally resolves on official outcomes, in some markets accelerated by media calls. Most of the time this difference is invisible. On a close, contested race, it can matter for timing and, in rare cases, outcome.

A live illustration of why the fine print matters: as of this snapshot our board's largest raw cross-venue gap is on a CLARITY Act tracker, where a Kalshi contract at 90 cents sits next to a Polymarket contract at 13.5 cents. No one actually disagrees by 76 points; the contracts ask different questions (a Senate vote by January versus a bill signed into law in 2026). Read the contract, not the headline. Our piece on the real cross-venue gaps separates the definitional mismatches from the genuine disagreements.

What the prices are doing right now

Two examples from the top of the board, as of this snapshot:

• Senate control: Polymarket prices Republican control at 54.5 cents and Democratic control at 45.5. Kalshi currently prices the same race the other way around, with Democratic control at 54.0: the two venues presently name different favorites on the cycle's headline question.
• House control: Polymarket prices Democrats to take the House at 91.5 cents; Kalshi prices the same outcome at 69.0, a 22.5 point gap on the same November.

We publish both venues side by side on every race precisely because "the market says" is sometimes two different numbers; the divergence between them is recomputed hourly.

Where the history comes from

Election market prices only mean something against their history: a 60-cent contract that was 40 last month tells a different story from one drifting down from 80. GhostLeg keeps durable daily price history back to January 2024 on the Polymarket side, which spans the 2024 presidential race, the largest settled election-market dataset of the modern era, and the 2025 governor races whose full price paths live on permanent record pages (New Jersey, Virginia). Since early August 2026, live prices on marquee races are also captured at 15-minute resolution.

That settled history is what lets us grade the markets rather than vibe about them; the graded calibration record, band by band, is its own post in this series.

How to read a GhostLeg race page

Each race page on the politics board puts the mechanics above into one view:

1. Both venues' current prices on matched outcomes, with candidate markets already summed to party level where needed
2. The divergence between them, signed and tracked hourly, so definitional gaps and real disagreements are visible as they develop
3. Price history charts from the durable daily candles
4. The Big Money card: the contract's current top-20 Polymarket holders, refreshed six-hourly (who the election whales are, and how to read them)

The pages run on the same data infrastructure that licenses GhostLeg's sports market feeds through the Data API.

FAQ

How do Polymarket election markets work? Each contract pays $1 if its exact outcome occurs and trades in cents until resolution; the price functions as the market's probability. Multi-candidate races list one contract per candidate, and party-level readings require summing same-party candidates.

Are the prices predictions? They are prices: the point where buyers and sellers currently balance. They function as probabilities, and our graded accuracy record measures how well. They are not predictions or recommendations, ours or anyone's.

Why do Polymarket and Kalshi show different prices for the same race? Different traders, fees, and resolution rules. Usually the gap is under 2 points; right now the chamber-control markets show much larger ones, which we track here.

Can Americans trade on Polymarket? Polymarket's structure has historically limited direct US participation; Kalshi is the US-regulated venue. GhostLeg is a data platform: we track and grade the markets, we do not take positions or wagers.

GhostLeg reports what prediction markets price. Prices are not predictions or recommendations. For entertainment purposes only. Past performance does not indicate future results.