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.
Who will run for the Republican presidential nomination in 2028?
Vol $2 today · $15.4K total
Will J.D. Vance win the 2028 Republican presidential nomination?
Vol $53.5K today · $16M total
Kalshi is 3 points higher than Polymarket (47% vs 44%). Polymarket trades about 26639.8× more volume today, so its price has more money behind it. They resolve on different dates (Jan 1 vs Nov 8), 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) | 47% | 44% |
| Change (24h) | +0.0 pt | -3.3 pt |
| Volume today | $2 | $53.5K |
| Total volume | $15.4K | $16M |
| Liquidity | — | $348.1K |
| Open interest | $8.3K | — |
| Resolves | 15mo | 25mo |
| Tracked for | 10 days | 10 days |
Resolution rules: read both before trusting a gap
Kalshi
If Thomas Massie announces a presidential campaign to contest the presidential nomination of the Republican party for the 2028 U.S. presidential election before Jan 1, 2028, then the market resolves to Yes.
Polymarket
This market will resolve to “Yes” if the named individual wins and accepts the 2028 nomination of the Republican Party for U.S. president. Otherwise, this market will resolve to “No”. The resolution source for this market will be a consensus of official Republican Party sources. Any replacement of the Republican nominee before election day will not change the resolution of the market.
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Informational only — not financial advice. Odds are mirrored from each platform and may lag the live order book.