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 Susan Wild be the Democratic nominee for the Senate in Pennsylvania?
Vol $0 today · $601 total
Will the Democratic Party control the Senate after the 2026 Midterm elections?
Vol $54.6K today · $4M total
Polymarket is 59 points higher than Kalshi (65% vs 6%). They resolve on different dates (Nov 7 vs Nov 4), 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.
| Kalshi | Polymarket | |
|---|---|---|
| Probability (Yes) | 6% | 65% |
| Change (24h) | +0.0 pt | +0.0 pt |
| Volume today | $0 | $54.6K |
| Total volume | $601 | $4M |
| Liquidity | — | $1.7M |
| Open interest | $518 | — |
| Resolves | 37mo | 17d |
| Tracked for | 9 days | 9 days |
Resolution rules: read both before trusting a gap
Kalshi
If Susan Wild wins the nomination for the Democratic Party to contest the 2028 Class III Pennsylvania Senate seat, then the market resolves to Yes.
Polymarket
This market will resolve according to the party that wins control of the United States Senate in the 2026 United States midterm election. A party wins control of the United States Senate if it wins a majority of the chamber’s voting seats. If no party wins a majority of voting seats, the party that wins control of the chamber is the party that wins half of the voting seats and holds the Vice Presidency. If the outcome remains ambiguous after applying the above criteria, the chamber will be deemed controlled by the party with which the first selected President Pro Tempore of the Congress that convenes after the specified election is affiliated. The following rules govern the counting of seats for determining which party wins control of the chamber. All regular and special Senate elections that determine representation in the upcoming 120th Congress and are scheduled to take place in November 2026 as of October 31, 2026 are included. Runoffs for qualifying elections will determine attribution of the relevant seat, even if they take place after November 2026. Vacant seats for which no election or special election to fill the seat is scheduled to take place in November 2026 as of October 31, 2026 will be treated as held by the party affiliation of the most recent member to hold that seat. For seats contested in the specified election, seats are attributed to the party under wh…
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Informational only — not financial advice. Odds are mirrored from each platform and may lag the live order book.