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 Republicans win the Senate race in Pennsylvania?
Vol $1 today · $3.4K total
Will oil be below $85 on November 2 and the Republicans win the Senate?
Vol $76.3K today · $158.1K total
Kalshi is 22 points higher than Polymarket (25% vs 2%). Polymarket trades about 86703.7× more volume today, so its price has more money behind it. 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) | 25% | 2% |
| Change (24h) | +0.0 pt | -5.7 pt |
| Volume today | $1 | $76.3K |
| Total volume | $3.4K | $158.1K |
| Liquidity | — | $264.6K |
| Open interest | $1.5K | — |
| Resolves | 37mo | 17d |
| Tracked for | 9 days | 5 days |
Resolution rules: read both before trusting a gap
Kalshi
If a representative of the Republican party is sworn in as a Senator of Pennsylvania for the term beginning in 2029, then the market resolves to Yes.
Polymarket
This market will resolve to "Oil < $85; R Senate" if oil is less than $85 at the close of trading on November 2, 2026, and the Republican Party wins control of the United States Senate in the 2026 United States midterm election. This market will resolve to "Oil < $85; D Senate" if oil is less than $85 at the close of trading on November 2, 2026, and the Democratic Party wins control of the United States Senate in the 2026 United States midterm election. This market will resolve to "Oil ≥ $85; R Senate" if oil is greater than or equal to $85 at the close of trading on November 2, 2026, and the Republican Party wins control of the United States Senate in the 2026 United States midterm election. This market will resolve to "Oil ≥ $85; D Senate" if oil is greater than or equal to $85 at the close of trading on November 2, 2026, and the Democratic Party wins control of the United States Senate in the 2026 United States midterm election. Oil price: The oil price component will be determined based on the Close price for the Active Month of ICE Futures Europe WTI Crude Futures (denoted by Pyth as "CLL") for the November 2, 2026 trading day. For a standard full trading session, the closing price refers to the Pyth "Close" value of the 1-minute candle corresponding to the final minute of regular trading hours on the primary exchange. Closing prices will be used exactly as published…
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Informational only — not financial advice. Odds are mirrored from each platform and may lag the live order book.