(Andrej Sokolow/Getty Images)

Anthropic releases Claude Fable 5, a locked-down, safer version of Mythos

Claude Fable 5 will cost twice as much as Claude Opus 4.8, Anthropic’s current flagship model. The company also released Claude Mythos 5, but only for trusted partners for testing.

Jon Keegan

6/9/26 1:36PM

Today Anthropic released the first public version of its next-generation AI model, Claude Fable 5. The company also announced Claude Mythos 5, but only for the small group of partners that are currently testing the new model. Both models are described as “Mythos-class” models by Anthropic.

In a press release, the company wrote:

“Fable 5’s capabilities exceed those of any model we’ve ever made generally available. It is state-of-the-art on nearly all tested benchmarks of AI capability, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas. The longer and more complex the task, the larger Fable 5’s lead over our other models.”

According to the company, Claude Fable 5 is heavily locked down, and is built with guardrails to keep it from being used to orchestrate the kind of novel cyberattacks that Anthropic had said it was capable of, a warning that set off a worldwide cybersecurity freak-out. Anthropic released benchmarks showing the models achieving substantially high scores on benchmarks for agentic coding, compared to leading models from OpenAI and Google.

While the company says Claude Fable 5 has been essentially kneecapped to remove the most potentially dangerous capabilities (it will defer any cybersecurity, biology, chemistry, or model distillation requests to Claude Opus 4.8), that hasn’t stopped Anthropic from charging a premium for the new models. According to the company, both Fable 5 and Mythos 5 will cost twice as much as Claude Opus 4.8, the current flagship model.

The release comes at a crucial moment for the company, as it recently filed confidentially for an IPO expected this year, and closed a funding round valuing it at $965 billion.

Yesterday, OpenAI also filed confidentially for a IPO, and both are expected to be among the largest IPOs in history.

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While gaming industry groups may not like it, there’s been a huge change in the methods people are using to put money on the big games, with everyone from fortunate NYC bar owners, to a far less fortunate Spanish supporter, turning to prediction markets to try and turn their sports know-how into cold, hard cash.

According to a new report from Adam Blacker for apptopia, that shift might have been even more seismic than imagined in the wake of the NBA and NHL finals and around the 2026 World Cup kicking off.

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Anthropic pulls Fable and Mythos access worldwide after Trump administration bars their use by foreign nationals

Only days after releasing two versions of its next-gen AI model, Anthropic has disabled them for users worldwide.

Anthropic says it received a Friday night order from the Trump administration to suspend access to the models for any foreign national (anywhere in the world) — a group that included some Anthropic employees. In response, the company turned off access to everyone.

Last week, the company released to the public its much-anticipated Claude Fable 5 model (and its restricted version Claude Mythos 5, which is still being tested with trusted partners). Anthropic said in a blog post announcing the action that officials cited national security concerns with the new models, while offering few specific details.

The post said that the government gave the company “verbal evidence of a potential narrow, non-universal jailbreak” of the public Fable 5 model. A jailbreak is a means by which users can evade restrictions built into the code to unlock prohibited functionality. Anthropic downplayed the significance of the attack, and said other major models, such as OpenAI’s GPT-5.5, could also be affected by the technique described.

Fears of these first Mythos-class models being misused are running high, after Anthropic warned the cybersecurity world in May that the advanced cyber capabilities of Mythos have rapidly discovered thousands of vulnerabilities in ubiquitous software, leading to the decision to restrict the full version of the model to a close group of trusted partners for testing.

This morning, Axios reported that Anthropic technical staff have flown to Washington to meet with White House officials to resolve the issue.

The Wall Street Journal is reporting that the Trump administration’s decision to take action against Anthropic was prompted by discussions that Amazon CEO Andy Jassy had with officials, including Treasury Secretary Scott Bessent. According to the report, Amazon researchers said they had been able to evade some of Fable 5’s security restrictions using specific prompts. Amazon is a major investor in Anthropic.

Anthropic is currently suing the US government to fight the Pentagon’s blacklisting of the company on national security grounds.

Statement on the US government directive to suspend access to Fable 5 and Mythos 5