Claude Mythos: Coding Arena Debut?

Platform comparison

Active sub-markets

Market context

Anthropic may release a new model called Claude Mythos and submit it to Arena.ai's public coding leaderboard sometime before the end of 2026. The market hinges on whether this model, once listed, achieves a specified performance threshold by noon ET on the day after its debut. A YES share pays out if both conditions are met; a NO share pays out if either fails—the model never appears, or it appears but underperforms the target.

The 99% implied probability reflects strong confidence that Anthropic will launch a Mythos-branded model and that it will meet the benchmark. Anthropic has established a pattern of releasing new Claude variants at regular intervals, with each successive generation typically improving on coding tasks. The Arena.ai leaderboard itself has become a standard benchmarking venue for major labs, making it a natural venue for Anthropic to showcase new capabilities. Historical precedent suggests that Anthropic's models, when released, tend to perform competitively on standardised coding evaluations, though the specific score threshold required here remains undisclosed in public materials.

Traders should monitor Anthropic's official announcements and product roadmap for any mention of Mythos-class models. The settlement window extends through 31 December 2026, providing a 24-month window for the event to occur. Key dependencies include whether Anthropic chooses to participate in Arena.ai's leaderboard (not guaranteed for every model release) and whether the company's development timeline aligns with the market's deadline. Recent industry practice shows major labs often announce new models via blog posts or developer documentation rather than press releases, so tracking Anthropic's official channels directly will be essential for early signal.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On Prediction Market UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Prediction Market UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.