Claude Mythos released by…?

Platform comparison

Active sub-markets

Market context

Anthropic confirmed on 26 March 2026 that Claude Mythos, an unreleased model described in a data leak as a significant capability jump in coding, reasoning, and cybersecurity tasks, has entered early access testing. The leak itself forced the company's hand; Anthropic had not publicly announced the model prior to the breach. This market asks whether the company will formally release Claude Mythos—or a model explicitly confirmed to be identical to the leaked version—by 30 April 2026, a window of just over one month from the leak date.

Anthropic's release cadence offers limited precedent for rapid public launches following internal breaches. Claude 3 family models (Opus, Sonnet, Haiku) rolled out over several weeks in early 2024, with staged availability across Anthropic's own API, Claude.ai, and third-party platforms. The current 0% implied probability on Polymarket reflects scepticism that a full public release follows a forced disclosure within such a compressed timeframe; traders on Kalshi and Smarkets show similar positioning, though Betfair's decimal odds format (around 100.0) makes the lay side more visible to casual browsers. Kalshi's tighter KYC requirements and US-only access mean its order book on this market remains thinner than Polymarket's.

Key catalysts centre on Anthropic's official announcements and API availability windows. The company typically signals release intent via blog posts and developer documentation updates; any such signal before mid-April would shift the probability substantially. Traders should monitor Anthropic's official channels and SEC filings (if any) for language confirming "general availability" versus continued "early access." Fee structures differ materially: Polymarket charges 2% on both sides, whilst Kalshi takes 0.4% per side, making small-margin trades more viable on the latter if conviction is low.

Methodology

We read Claude Mythos released by…? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative 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.

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.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket Alternative UK 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.