Anthropic’s rapid iteration on its Mythos series drives current trader sentiment, with the September 1, 2026 release of Claude Mythos 5.1 following the June launch of Mythos 5 and Fable 5. These models lead the September 2026 HLE leaderboards at 64.5–65% accuracy, outpacing GPT-5.4 Pro and Gemini variants on the 2,500-question expert-level benchmark spanning mathematics, physics, and other domains. The series emphasizes restricted high-capability releases for cybersecurity and biology use cases, creating competitive pressure among frontier labs to demonstrate reasoning gains on HLE without tool assistance. Upcoming catalysts include further leaderboard refreshes, potential Mythos 5.1 evaluations, and any shifts in Anthropic’s trusted-access rollout that could accelerate or delay public benchmarking visibility.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated$12,767 Vol.
45%+
97%
50%+
97%
55%+
55%
60%+
9%
$12,767 Vol.
45%+
97%
50%+
97%
55%+
55%
60%+
9%
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".
Market Opened: Sep 1, 2026, 11:31 AM ET
Resolution Source
https://agi.safe.ai/Resolver
0x65070BE91...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".
Resolution Source
https://agi.safe.ai/Resolver
0x65070BE91...Anthropic’s rapid iteration on its Mythos series drives current trader sentiment, with the September 1, 2026 release of Claude Mythos 5.1 following the June launch of Mythos 5 and Fable 5. These models lead the September 2026 HLE leaderboards at 64.5–65% accuracy, outpacing GPT-5.4 Pro and Gemini variants on the 2,500-question expert-level benchmark spanning mathematics, physics, and other domains. The series emphasizes restricted high-capability releases for cybersecurity and biology use cases, creating competitive pressure among frontier labs to demonstrate reasoning gains on HLE without tool assistance. Upcoming catalysts include further leaderboard refreshes, potential Mythos 5.1 evaluations, and any shifts in Anthropic’s trusted-access rollout that could accelerate or delay public benchmarking visibility.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated


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