Claude Mythos METR 50% time horizon

Question

This market will resolve to the highest 50% time horizon, as reported by METR, for the first Claude Mythos model to appear on METR's graph.

'Mythos' includes any Claude model that sits above 'Opus' in Anthropic's naming scheme, even if Anthropic ends up calling it something other than Mythos.

50% time horizon is a measure of AI autonomy based on the length of tasks that AI can do: roughly, it is the time that humans take to complete tasks that an AI system can successfully do 50% of the time. See METR's "Measuring AI Ability to Complete Long Tasks" for the technical definition. Claude 3.7 Sonnet, released in February 2025, was the leading model with a 50% horizon of 59 minutes.

[image]Left bounds inclusive, right bounds exclusive.

Update 2026-03-29 (PST) (AI summary of creator comment): Resolves N/A if no qualifying model is released by September 30th (2026).

Manifold Markets · Answer

Per Manifold Markets prediction market, Other, followed by 20h–22h and 22h–24h are most likely. See the market for live updates (4 traders, as of Mar 29, 2026).

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