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Before Jan 1, 2028 63%
Next is Yes at 58%. The venues list this event, but none of their outcomes are matched yet, so prices are shown separately.
Consensus blends each venue’s last price, weighted by how much has traded there. Best Yes price is the cheapest ask across venues, and the payout is what a winning $100 stake returns before fees. Open a row for each venue’s contract name, bid and ask, and how closely their rules match.
Prices come from our regular polls of each venue, the oldest 9 min ago. Ages are as of when this page was built.

The top 3 outcomes on both venues, with the consensus between them. Hover for exact values.
Each venue’s resting orders for the selected outcome’s Yes contract, side by side. Top of book streams live; depth refreshes every 15 seconds.
Polymarket doesn’t list Before Jan 1, 2028 for this event.
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Enter a stake to see where it buys the most after fees, using each venue’s live order book.
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Buys at the asks resting now (taker orders), cheapest after fees first, from order-book snapshots up to 15 seconds old. Fees: Kalshi 0.07 × price × (1 − price) per share, rounded up to the cent; Polymarket 0.05 × price × (1 − price) per share (other / general rate). Fee calculator. Estimates only, not advice.
Live prediction market odds for "OpenAI vs. Anthropic: First to another Millennium Prize?". Before Jan 1, 2028 leads at 63%. Next is Yes at 58%. $123K has traded across 3 outcomes on Kalshi and Polymarket. The market is expected to resolve by Jan 1, 2028.
This market will resolve to "OpenAI" if OpenAI, or an official representative of OpenAI, announces that OpenAI has solved a qualifying Millennium Prize Problem by December 31, 2027, 11:59 PM ET before Anthropic does so. This market will resolve to "Anthropic" if Anthropic, or an official representative of Anthropic, announces that Anthropic has solved a qualifying Millennium Prize Problem by December 31, 2027, 11:59 PM ET before OpenAI does so. If neither company makes a qualifying announcement by December 31, 2027, 11:59 PM ET, or if both make qualifying announcements on the same calendar day, this market will resolve 50-50. A qualifying announcement by any other company does not end the race or affect resolution. 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 the company, its researchers, or its models, alone or jointly with outside researchers. An announcement that only credits or congratulates outside researchers, including researchers who used the company'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 Anthropic and/or their official representatives; however, a consensus of credible reporting may also be used.
It is the price of a Yes contract that pays $1 if the outcome happens. A 14¢ price means traders put the chance near 14%. Where two venues list the same outcome, we blend their last prices, weighting the venue with more trading volume more heavily (neither counts for less than a quarter). When only one outcome can win, each venue’s prices add up to a little over 100% (its margin); the fair chance removes that margin so the outcomes add up to exactly 100%.
A Yes contract pays $1 if it wins, so at the best ask a $100 stake buys 100 ÷ ask contracts. At 18¢ that is about 555 contracts, paying $556 (5.56x) if Yes happens. Venue fees and price slippage on larger orders are not included.
Each venue has its own traders, fees and order book. Contracts can also settle on slightly different terms, which is why each row lists how closely the rules match.
Only when you can buy Yes on one venue below what someone pays for Yes on the other, after fees, and both contracts settle the same way. We show the executable bid and ask so you can check.
Venue prices refresh every few minutes, and the order book and live quotes stream continuously. Each venue’s card shows when we last observed it.