Anthropic confirmed it is developing a new top-tier AI model called Claude Mythos after draft materials were leaked online. The company described Mythos as its most capable model yet, with dramatic improvements in coding and cybersecurity. This news triggered a sell-off in cybersecurity stocks, as internal documents warned the model’s capabilities could outpace current defenses.
A leaked draft post revealed that Anthropic is developing its most powerful AI model to date, called Claude Mythos. The model introduces a new tier above Opus, internally referred to as “Capybara.”
Anthropic confirmed the model’s existence after unpublished files were discovered in a publicly accessible data cache. “We’re developing a general purpose model with meaningful advances in reasoning, coding, and cybersecurity,” an Anthropic spokesperson stated.
The company attributed the exposure to human error in configuring its content tools. According to an archived page, Anthropic called Mythos “the most powerful AI model we’ve ever developed.”
The draft materials highlighted the system’s significant cybersecurity implications. “Although Mythos is currently far ahead of any other AI model in cyber capabilities, it presages an upcoming wave of models that can exploit vulnerabilities in ways that far outpace the efforts of defenders,” the company wrote.
News of the leak quickly spilled into financial markets, causing shares of several cybersecurity firms to drop. Stocks including Palo Alto Networks, CrowdStrike, Zscaler, and Fortinet all declined during Friday trading.
This sell-off echoes a similar market response to a previous Anthropic product reveal in February. The introduction of Claude Cowork at that time triggered a broad sell-off across software and professional-services companies.
That earlier event erased roughly $285 billion in market value as investors reassessed AI’s impact. “The market’s response was a signal… that investors are finally pricing in the structural risk that foundation model providers can now compete directly with the software layer,” analyst Scott Dylan noted at the time.
