Polymarket vs. Kalshi
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See where the two biggest prediction markets disagree. Pick any two markets, or start from the biggest gaps below: prices, volume, history and the resolution rules, side by side.
Will the Republicans win the Idaho Senate race in 2026?
Vol $115.2K today · $242.1K total
Polymarket is 7 points higher than Kalshi (97% vs 90%). They resolve on different dates (Nov 4 vs Nov 7), so they may not be exactly the same bet.
History starts when we first saw each market, so a newly added market has a short line.
| Polymarket | Kalshi | |
|---|---|---|
| Probability (Yes) | 97% | 90% |
| Change (24h) | +5.1 pt | -1.1 pt |
| Volume today | $115.2K | $0 |
| Total volume | $242.1K | $417 |
| Liquidity | $105.9K | — |
| Open interest | — | $346 |
| Resolves | 12d | 37mo |
| Tracked for | 12 hours | 13 days |
Resolution rules: read both before trusting a gap
Polymarket
This market will resolve according to the winner of the 2026 midterm Idaho U.S. Senate election, inclusive of any run-offs. A candidate shall be considered to represent a party in the event that he or she is the nominee of the party in question. Candidates other than the Democratic or Republican nominee (e.g., Greens, Libertarian, independent) may be added at a later date. Candidates who run as independents will not be encompassed by the “Democrat” or “Republican” options regardless of any affiliation they may have with the party. The candidates may be named in the contract for the convenience of traders. In the event that any named candidate is replaced as the nominee of their respective party prior to election day, the name in the contract will be updated and the market will resolve based on the replacement nominee of the party. The resolution source for this market is the Associated Press, Fox News, and NBC. This market will resolve once all three sources call the race for the same candidate. If all three sources haven’t called the race in this state for the same candidate, this market will resolve based on the official certification.
Kalshi
If a representative of the Democratic party is sworn in as a Senator of California for the term beginning in 2029, then the market resolves to Yes.
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Informational only — not financial advice. Odds are mirrored from each platform and may lag the live order book.