Kalshi adds accuracy scores and low-volume warnings to its midterm election markets
Kalshi now shows a Brier score, a low-volume tag and live trades on every midterm market. Why it made the change, the candidates it has banned for betting on themselves, and how much is being traded on the 2026 elections.
Kalshi added three transparency features to every US midterm election market in early October 2026, a month before the 3 November vote:
- Brier scores: an accuracy score for each market, calculated from Kalshi's historical data and weighted by volume and time to resolution. Lower is better (what a Brier score is).
- Low-volume tags: labels showing each market's total volume and flagging markets with few traders, where a handful of trades can move the price.
- Live trade displays: individual trades shown as they happen, so visitors can see how a price forms.
Why now
Coverage linked the timing to August's Wisconsin Democratic primary for governor, where Kalshi's market gave the eventual winner only about 4%. Thin markets like that one can look authoritative when they appear on TV or social media; a low-volume warning tells readers how much weight a price deserves (are prediction markets accurate?).
Candidates betting on themselves
Kalshi says every account is identity-verified so it can screen out insiders. In 2026 it has fined and suspended four congressional candidates for trading on their own races, three in April and one in August, with bans of three to five years.
How big midterm trading has become
An analysis by Reuters with the Anti-Corruption Data Collective counted more than $220 million wagered on the 2026 midterms across Kalshi and Polymarket through 30 September, spread over more than 21,000 markets, compared with 463 markets tracked in the 2024 cycle. On Polymarket, the top 1% of wallets accounted for about 70% of congressional election volume.
Follow the races: 2026 election odds · live election odds · California governor · Ohio governor.
