Anthropic has released its Claude Opus 5.5 model, offering less expensive outputs than the previous Opus release with performance comparable to the larger Fable model, as it prepares for a Wall Street debut expected in the coming weeks.

The company said Opus 5.5 performs similarly to Fable 5.1 on most work while costing $20 (£15) per million output tokens, compared to $25 for the previous Opus release.

Price, performance

Fable is a model in Anthropic’s largest model class, Mythos, that has safety guardrails added for public use.

Opus is Anthropic’s next-most-capable model class, followed by the smaller Sonnet and Haiku classes.

The new release of Opus outpaced Fable 5.1 on some benchmarks and completed many informal tasks that Fable failed to carry out, Anthropic said.

Opus 5.5 also runs more quickly than the previous Opus release, reflecting the reduced computing resources needed to power it, said the company.

Open-weight competition

Anthropic released Opus 5 on 24 July. It said it plans to release Sonnet 5.5 and Haiku 5.5 in the coming weeks, with similar performance enhancements.

The company faces intense competition from OpenAI and a range of high-performance, low-cost open-weight models developed in China, at a time when companies are seeking ways to control soaring AI costs.