METR finds Anthropic models accelerating R&D in 11-week probe
The safety group says Anthropic's progress is speeding up about twice as fast as a year ago, and that three trained models remain unreleased.
METR published a report on an 11-week investigation conducted inside Anthropic, concluding that the company's AI models are accelerating its own research and development, according to the safety research organization. The report also states that Anthropic has finished training three unreleased models, referred to as Model 2, Model 3 and Model 4.
METR said its benchmark scores suggest Anthropic made roughly two years of historical progress over the last year, with its models improving about twice as quickly as they were a year earlier. The researchers said they are confident the acceleration was not simply the result of scaling up computing power, and that the majority of it as of October is due to AI.
Employees using Anthropic's most capable internal model self-reported being around 12 times as productive, according to METR. The report also identifies an unreleased model dating back to 2022, called Unreleased 2022.
Anthropic was permitted to redact portions of the final METR report, the organization said.
The probe is separate from a METR program that offers safety researchers employee-like access to systems, which followed high-profile hacking incidents over the summer. In October 2025, employees reported roughly double the productivity gains a few months earlier while using Mythos 5, compared with the newer internal model.
Company context
Anthropic is preparing to go public, while CEO Dario Amodei has publicly called for labs to slow AI development.
Quick answers
What did METR find in its Anthropic investigation?
METR said Anthropic's models are improving about twice as quickly as a year ago, and that benchmark scores suggest roughly two years of historical progress over the last year. It said the majority of the acceleration as of October is due to AI.
How many unreleased models does Anthropic have?
According to METR, Anthropic has finished training three unreleased models, codenamed Model 2, Model 3 and Model 4. The report also identifies an unreleased model from 2022 called Unreleased 2022.
Could Anthropic edit the METR report?
Yes. METR said Anthropic was permitted to redact portions of the final report.