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 Republican party win the House, the Democratic party win the Senate, and the Democratic party win the Presidency?
Vol $0 today · $36.9K total
Will there be a Hormuz agreement and the Democrats win the Senate?
Vol $93.8K today · $494K total
Polymarket is 2 points higher than Kalshi (3% vs 1%). 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) | 1% | 3% |
| Change (24h) | +0.0 pt | -6.9 pt |
| Volume today | $0 | $93.8K |
| Total volume | $36.9K | $494K |
| Liquidity | — | $55.6K |
| Open interest | $25K | — |
| Resolves | 37mo | 15d |
| Tracked for | 11 days | 9 days |
Resolution rules: read both before trusting a gap
Kalshi
If the Republican party wins the House, the Democratic party wins the Senate, and the Democratic party wins the Presidency in the 2028 election, then the market resolves to Yes.
Polymarket
This market will resolve to "Hormuz Agreement; R Senate" if a Hormuz Agreement is announced by October 23, 2026, 11:59 PM ET, and the Republican Party wins control of the United States Senate in the 2026 United States midterm election. This market will resolve to "Hormuz Agreement; D Senate" if a Hormuz Agreement is announced by October 23, 2026, 11:59 PM ET, and the Democratic Party wins control of the United States Senate in the 2026 United States midterm election. This market will resolve to "No Hormuz Agreement" immediately if a Hormuz Agreement is not announced by October 23, 2026, 11:59 PM ET. Hormuz Agreement: A "Hormuz Agreement" will be considered to have occurred if a diplomatic agreement between the United States and Iran over traffic in the Strait of Hormuz is announced by October 23, 2026, 11:59 PM ET. A diplomatic agreement refers to an official agreement, treaty, deal, or substantially similar diplomatic instrument that establishes agreed actions, policies, obligations, or commitments between the United States and Iran. A qualifying diplomatic agreement must establish Iranian policies, obligations, or commitments aimed at permitting, restoring, or increasing vessel or shipping traffic through the Strait of Hormuz. All listed countries must announce their acceptance of the same qualifying diplomatic agreement for the Hormuz Agreement component to be met. A …
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Informational only — not financial advice. Odds are mirrored from each platform and may lag the live order book.