Claude Mythos: Coding Arena Debut?

Platform comparison

Active sub-markets

Market context

Anthropic's forthcoming Claude Mythos model family will either debut on Arena.ai's Coding Leaderboard before year-end 2026 or it won't. The market hinges on whether a model bearing the Mythos designation appears in the ranked list and achieves a specified performance threshold within 24 hours of its first listing. The 99% crowd probability reflects widespread expectation that Anthropic will release Mythos variants and submit them to the benchmark during the settlement window.

Historical precedent suggests caution around such high probabilities. Anthropic's previous model releases—Claude 3 Opus, Sonnet, and Haiku—arrived with staggered timelines and selective benchmark participation. The company has occasionally delayed public leaderboard submissions despite model availability, prioritising internal evaluation or staged rollouts. Comparable AI labs have missed self-imposed release windows or chosen alternative benchmarking platforms, reducing the certainty that any given model class reaches a specific public leaderboard by a fixed date.

Traders should monitor Anthropic's official announcements and product roadmap statements, particularly any public commitments regarding Mythos release timing. Arena.ai's leaderboard update frequency and submission protocols matter operationally—delays in processing new model entries could affect settlement interpretation. The specification score threshold, which determines whether a debut qualifies, remains critical; a Mythos model could appear on the leaderboard yet fail to meet the performance bar, triggering a "No" resolution despite the model's existence. Watch for any clarification from Anthropic on Mythos positioning within their product hierarchy, as naming conventions will determine eligibility.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Champions League Prediction, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Champions League Prediction, 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.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Champions League Prediction triggers a quick verification flow that finishes in 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.