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 OpenAI announce another Millennium Prize solution by December 31, 2027?
Vol $50.2K today · $473.8K total
Will any AI lab solve a Millennium Prize Problem before Jul 1, 2027?
Vol $204 today · $715 total
Polymarket is 3 points higher than Kalshi (53% vs 50%). Polymarket trades about 245.7× more volume today, so its price has more money behind it. They resolve on different dates (Jan 1 vs Jul 1), 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) | 53% | 50% |
| Change (24h) | +4.0 pt | +6.5 pt |
| Volume today | $50.2K | $204 |
| Total volume | $473.8K | $715 |
| Liquidity | $17.3K | — |
| Open interest | — | $608 |
| Resolves | 14mo | 8mo |
| Tracked for | 34 hours | 19 days |
Resolution rules: read both before trusting a gap
Polymarket
This market will resolve to "Yes" if OpenAI, or an official representative of OpenAI, announces that OpenAI has solved any of the qualifying Millennium Prize Problems between market creation and the specified date, 11:59 PM ET. Otherwise, this market will resolve to "No". The qualifying problems are the Riemann Hypothesis, P versus NP, the Yang-Mills existence and mass gap problem, the Hodge Conjecture, and the Birch and Swinnerton-Dyer Conjecture (https://www.claymath.org/millennium-problems/). Announcements concerning the Navier-Stokes existence and smoothness problem will not qualify. A qualifying announcement must express that the problem has been solved; announcements of partial results or progress toward a solution will not qualify. The announcement must present the solution as the work of OpenAI, its researchers, or its models, alone or jointly with outside researchers. An announcement that only credits or congratulates outside researchers, including researchers who used OpenAI's models, compute, or research credits, will not qualify. No further confirmation from Clay Math Institute or any other organization is required. The primary resolution source for this market will be official information from OpenAI and/or its official representatives; however, a consensus of credible reporting may also be used.
Kalshi
If any AI lab solves another Millennium Prize Problem after Issuance and before Jul 1, 2027, 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.