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Business Insider

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Substack

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Verge

Anthropic releases its first Mythos-class model Claude Fable

Anthropic

Claude Fable 5 and Claude Mythos 5

Anthropic releases Claude Fable 5, a 'Mythos-class' AI model with safeguards

ZDNET

Anthropic's new Claude Fable 5 is the same base model as Mythos but with guardrails attached

Yahoo Finance

Anthropic launches Mythos-class Claude Fable 5 model, available to the public

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Anthropics Claude Fable 5 is a version of Mythos the public can access today

The Wall Street Journal

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Guardian

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Amazon Web Services

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Six Reasons Claude Mythos Is an Inflection Point for AIand Global Security

Anthropic launched Claude Fable 5 on Tuesday, the first publicly available version of its Mythos-class AI model. The release follows the April debut of Claude Mythos Preview, which was restricted to a limited group of partners under Project Glasswing due to <a target="_blank" rel="noopener noreferrer nofollow" href="https://www.verity.news/story/2026/anthropic-probes-unauthorized-access-to-claude-mythos-ai">cybersecurity concerns.</a>

Anthropic launched Claude Fable 5 on Tuesday, the first publicly available version of its Mythos-class AI model. The release follows the April debut of Claude Mythos Preview, which was restricted to a limited group of partners under Project Glasswing due to cybersecurity concerns.

Fable 5 uses safety classifiers that route queries related to cybersecurity, biology, chemistry and distillation to the less powerful Claude Opus 4.8 model instead. Anthropic said early data shows at least 95% of Fable 5 sessions run entirely on the model's own responses, with no fallback.

Fable 5 uses safety classifiers that route queries related to cybersecurity, biology, chemistry and distillation to the less powerful Claude Opus 4.8 model instead. Anthropic said early data shows at least 95% of Fable 5 sessions run entirely on the model's own responses, with no fallback.

Anthropic conducted more than 1,000 hours of external bug bounty testing and engaged outside red-teaming organizations, neither of which found a universal jailbreak for Fable 5. The U.K. AI Safety Institute made progress toward one within an initial testing window, Anthropic acknowledged.

Anthropic conducted more than 1,000 hours of external bug bounty testing and engaged outside red-teaming organizations, neither of which found a universal jailbreak for Fable 5. The U.K. AI Safety Institute made progress toward one within an initial testing window, Anthropic acknowledged.

Alongside Fable 5, Anthropic released Claude Mythos 5 — the same underlying model but with safeguards lifted in some areas — initially available only to Project Glasswing partners, including firms such as Amazon Web Services, Apple, Google, Microsoft and JPMorgan Chase.

Alongside Fable 5, Anthropic released Claude Mythos 5 — the same underlying model but with safeguards lifted in some areas — initially available only to Project Glasswing partners, including firms such as Amazon Web Services, Apple, Google, Microsoft and JPMorgan Chase.

Both Fable 5 and Mythos 5 are priced at $10 per million input tokens and $50 per million output tokens, roughly double the cost of Claude Opus 4.8 but about half the price of Claude Mythos Preview. Anthropic requires 30-day data retention for all traffic on Mythos-class models.

Both Fable 5 and Mythos 5 are priced at $10 per million input tokens and $50 per million output tokens, roughly double the cost of Claude Opus 4.8 but about half the price of Claude Mythos Preview. Anthropic requires 30-day data retention for all traffic on Mythos-class models.

The Fable 5 launch comes as <a target="_blank" rel="noopener noreferrer nofollow" href="https://www.verity.news/story/2026/anthropic-files-for-ipo-ahead-of-openai">Anthropic confidentially filed IPO</a> paperwork with the SEC and reported a revenue run rate of $47 billion, up from $10 billion the prior year. A recent funding round valued Anthropic at $965 billion, surpassing rival OpenAI's March valuation of $852 billion.

The Fable 5 launch comes as Anthropic confidentially filed IPO paperwork with the SEC and reported a revenue run rate of $47 billion, up from $10 billion the prior year. A recent funding round valued Anthropic at $965 billion, surpassing rival OpenAI's March valuation of $852 billion.

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Claude Fable 5 is a genuine step-change, not marketing fluff — it benchmarks at the top in every respect by a clear margin and feels, qualitatively, like a true collaborative leap forward. Long, difficult problem-solving sessions hit differently now; the model just gets ambitious tasks and runs with them. This is the kind of release that actually shifts how software gets built.

Claude Fable 5 is a genuine step-change, not marketing fluff — it benchmarks at the top in every respect by a clear margin and feels, qualitatively, like a true collaborative leap forward. Long, difficult problem-solving sessions hit differently now; the model just gets ambitious tasks and runs with them. This is the kind of release that actually shifts how software gets built.

Alex Albert

Andrej Karpathy

Claude Fable 5 is a pricing stunt disguised as a breakthrough — Anthropic is doubling costs to create a premium tier, while the safety concerns are overblown nonsense. Chinese open-source models are closing the gap for a fraction of the price, exposing how unsustainable the cash-burning business model really is. The AI hype machine is running on fumes, not genuine innovation.

Claude Fable 5 is a pricing stunt disguised as a breakthrough — Anthropic is doubling costs to create a premium tier, while the safety concerns are overblown nonsense. Chinese open-source models are closing the gap for a fraction of the price, exposing how unsustainable the cash-burning business model really is. The AI hype machine is running on fumes, not genuine innovation.

Aurea Libe

There's a 50% chance that a large language model with a context window of at least 5 million tokens will be freely accessible to anyone by Nov. 1, 2026, according to the Metaculus prediction community.

There's a 50% chance that a large language model with a context window of at least 5 million tokens will be freely accessible to anyone by Nov. 1, 2026, according to the Metaculus prediction community.

AI: Chatbots

AI: Safety and Regulations

Claude via X

Claude via X

Anthropic Launches Claude Fable 5 With Safety Guards

Artificial Intelligence

Science & technology

United States of America

Fable 5 is the result of 1,000+ hours of external red-teaming and bug bounties that found no universal jailbreak. Classifiers route the narrowest high-risk queries to safer models; 95%+ of sessions run on full frontier capability. Mythos 5 stays restricted to vetted partners until hardening is complete. Tiered release with independent oversight is the closest thing the industry has to a responsible deployment standard.

Fable 5 is the result of 1,000+ hours of external red-teaming and bug bounties that found no universal jailbreak. Classifiers route the narrowest high-risk queries to safer models; 95%+ of sessions run on full frontier capability. Mythos 5 stays restricted to vetted partners until hardening is complete. Tiered release with independent oversight is the closest thing the industry has to a responsible deployment standard.

Classifier-based mitigations don't solve the underlying problem — they delay it. The UK AISI made jailbreak progress within the initial testing window, and no red-teaming regime has reliably predicted real-world adversarial behavior at scale. Autonomous zero-day exploitation is a qualitatively different risk category. The question isn't whether Fable 5 is safe enough — it's whether this capability class should be deployed publicly at all.

Classifier-based mitigations don't solve the underlying problem — they delay it. The UK AISI made jailbreak progress within the initial testing window, and no red-teaming regime has reliably predicted real-world adversarial behavior at scale. Autonomous zero-day exploitation is a qualitatively different risk category. The question isn't whether Fable 5 is safe enough — it's whether this capability class should be deployed publicly at all.

Anthropic spent two months warning the world that Mythos was too dangerous to release — then shipped it to anyone with a credit card. The safety classifier complaints that followed were mostly about over-triggering on benign queries, not dangerous ones. With a confidential IPO filing, a $965B valuation, and full Mythos 5 access reserved for elite partners, the gap between the rhetoric and the reality is doing a lot of work for Anthropic's market positioning.

Anthropic spent two months warning the world that Mythos was too dangerous to release — then shipped it to anyone with a credit card. The safety classifier complaints that followed were mostly about over-triggering on benign queries, not dangerous ones. With a confidential IPO filing, a $965B valuation, and full Mythos 5 access reserved for elite partners, the gap between the rhetoric and the reality is doing a lot of work for Anthropic's market positioning.

Anthropic Releases Claude Mythos AI Model to Public With Safety Guards

Anthropic LaunchesReleases Claude FableMythos 5AI Model to Public With Safety Guards

The Spin

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