Anthropic unveils Opus 5.5, beating Fable in benchmarks and cutting token prices
Anthropic released its new frontier model, Opus 5.5, on September 22, 2026. The company said the model sets new state-of-the-art results in coding and knowledge work benchmarks, outperforming the larger Fable model across many tests and succeeding on informal tasks that Fable failed to complete.
The new model is also cheaper than its predecessor. Output tokens are priced at $20 per million, down from $25 for the previous version, with similar reductions across other pricing metrics. Anthropic said Opus 5.5 is faster to run, reflecting an overall drop in the compute required to serve it.
The update also changes how the model communicates: Opus 5.5 is less likely to use jargon and more likely to put important information at the start of its messages. The launch comes about two months after Opus 5 arrived on July 24, 2026. Anthropic said Sonnet 5.5 and Haiku 5.5 will follow in the coming weeks with similar performance improvements.
Anthropic said Opus 5.5's capabilities in biology and cybersecurity are comparable to those of Mythos, so its release is subject to the same safeguards applied to Fable. Those limits restrict use of the model for tasks such as discovering exploits in compiled programs or developing recognizable biological weapons.
Opus 5.5 is Anthropic's first model release since CEO Dario Amodei endorsed calls to pace the frontier. In a post earlier this month, Amodei wrote that addressing risks requires more prudence, including not only investing in risk prevention but pacing capabilities advancement so that risk prevention can keep up.
Anthropic said Opus 5.5's safety training was broadly similar to its predecessors, with alignment testing and pre-release evaluation by outside groups including METR and Frontier Design. The company added that it is already preparing more advanced training and evaluation systems, including improved security and monitoring, for future models.
