- Will the next Mythos-Class model debut with a Humanity's Last Exam score of 45% or higher?94¢
- Will the next Mythos-Class model debut with a Humanity's Last Exam score of 50% or higher?92¢
- Will the next Mythos-Class model debut with a Humanity's Last Exam score of 55% or higher?56¢
- Will the next Mythos-Class model debut with a Humanity's Last Exam score of 60% or higher?9¢
This market will resolve to "Yes" if the next Anthropic Mythos-class model added to the Humanity's Last Exam results at https://agi.safe.ai/ has an HLE Accuracy of at least the specified percentage at 12:00 PM ET on the calendar date following the date on which it first appears on the site. Otherwise, this market will resolve to "No". Any model whose official name includes "Mythos," or "Fable" (e.g., Claude Fable 5.1 or Claude Fable 6), or that Anthropic officially describes as a "Mythos-class" model or similar, will qualify for this market's resolution. Anthropic's other model tiers, such as Opus, Sonnet, or Haiku, will not qualify. The percentage displayed as "HLE Accuracy" for the model in its result card on the "AI Progress on Humanity's Last Exam" chart at https://agi.safe.ai/ will be used to resolve this market. This market will resolve solely based on the displayed HLE Accuracy, regardless of the model's Calibration Error, chart position, other configuration scores, or any underlying granular or unrounded data presented elsewhere. If multiple qualifying models are added to the Humanity's Last Exam results on the same calendar date (ET), the model with the highest HLE Accuracy will be used for resolution. Models added to the results on the calendar date following the initial qualifying model's first appearance will not be considered. If a model is first added to the Humanity's Last Exam results but is subsequently removed and not re-added, such that it is not displayed on the site at 12:00 PM ET on the calendar date following its first appearance, its appearance will not qualify as added to the Humanity's Last Exam results. A qualifying model must be newly added to the Humanity's Last Exam results at https://agi.safe.ai/. Whether the model was previously released, publicly accessible, in beta, or otherwise available before appearing on the site is irrelevant for this market. The resolution source for this market is the official Humanity's Last Exam website found at https://agi.safe.ai/. If this resolution source is unavailable at 12:00 PM ET on the calendar date following the date on which the qualifying model first appears on the site, this market will resolve based on the first subsequent instance at which the model's HLE Accuracy becomes available on the site. If it remains unavailable through the end of the seventh day after the qualifying model first appears on the site or if no qualifying model is added by December 31, 2026, 11:59 PM ET, this market will resolve to "No".
Anthropic’s September 1 release of Claude Mythos 5.1—the latest in its restricted-access frontier series optimized for cybersecurity and biology—has become the dominant catalyst for trader views on the next Mythos-class model’s Humanity’s Last Exam (HLE) debut. The model follows the June 2026 launch of the safer Fable 5 public variant and continues Anthropic’s pattern of rapid capability gains, with Fable 5.1 already posting the top HLE score at 65 percent on the September 2026 leaderboard, narrowly ahead of Opus 5 and Mythos 5. HLE’s expert-crafted, low-saturation questions across 100+ domains remain a key frontier signal, and traders are watching whether the new Mythos 5.1 receives an official evaluation or if Anthropic prioritizes internal partner testing before public benchmark disclosure. Upcoming partner-program expansions and any follow-on announcements could shift timing expectations.