Anthropic launches Fable 5.2 and Mythos 5.2 ahead of IPO

On Monday, Anthropic rolled out updated versions of its Fable and Mythos AI models while gearing up for an IPO planned for later this month. The new Fable 5.2 and Mythos 5.2 are as much as 30% quicker than the previous generation on demanding work such as coding, and cost 20% less, according to the company.

Fable 5.2 can handle more complex software engineering work, control robots, manage long-running projects and coordinate more than 1,000 AI agents at the same time, according to Anthropic. Mythos 5.2 has lighter safety limits for cybersecurity and life sciences uses, and organizations can get access through a verification program.

Fable 5.2 costs $8 for every million input tokens and $40 for every million output tokens, down from $10 and $50 for version 5.1. Both models operate faster than their predecessors, and Anthropic said Fable 5.2 costs less than the earlier version.

Anthropic said in a post that the models improve coding, reasoning and vision. During prerelease testing, the models helped engineers complete software migrations that were otherwise infeasible, designed three working electronic devices from scratch, resolved two open problems in black hole physics, advanced robotics evaluations substantially and formalized the proof of Fermat's Last Theorem in 30 hours. The company also said restrictions during training curbed research skills that might speed up AI development directly.

Anthropic first launched Mythos in April, limiting access to government bodies, financial institutions and large software providers because the model could find and take advantage of security holes in important software. Fable followed two months later with comparable abilities for a wider market, although its cybersecurity functions were switched off. In June, Washington limited access to both models over safety concerns. Anthropic later added classifiers that spot and stop cybersecurity work, after which Fable 5 access returned and Mythos 5 access was restored for a small set of users.

Dianne Penn, head of research product management at Anthropic, said the latest models went through longer test periods and extra evaluation methods. "Pacing is not like pausing," Penn said. Penn said Anthropic is widening Mythos access, offering the new version to companies in the US and abroad.

A securities filing earlier this month showed that third-quarter revenue reached $17 billion, up from $1.4 billion a year earlier, while the company posted an operating loss of $567 million partly because it spent more on short-term computing resources. The company's valuation expectations for the IPO exceed $1 trillion, but projections have dropped recently from a peak of $2 trillion. Sales growth slowed from previous quarters amid competition from OpenAI and cheaper models, many from China.