{"slug": "anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it", "title": "Anthropic Calls Claude Opus 5.5 'Strongest-Performing Model We've Tested' as It Makes New Safety Claims", "summary": "Anthropic launched Claude Opus 5.5 on Tuesday, cutting list prices 20 per cent versus Opus 5 to $4 per million input tokens and $20 per million output tokens, with cache reads down 60 per cent to 20 cents per million tokens. Anthropic said the model matches its top-tier Claude Fable 5.1 on most tasks, produces output more than 30 per cent faster, and was around 85 per cent less likely than Opus 5 or Claude Mythos 5.1 to attempt to bypass containment boundaries in an internal evaluation. The release comes as Anthropic prepares for a potential initial public offering, with reports suggesting a valuation approaching $2 trillion, after a $65 billion Series H round in May and a $965 billion valuation in its most recent private funding round.", "body_md": "# Anthropic Calls Claude Opus 5.5 'Strongest-Performing Model We've Tested' as It Makes New Safety Claims\n\n## The company says its latest flagship model is faster and more resistant to prompt injection, as competition intensifies from OpenAI and Chinese AI developers\n\nAnthropic has cut list prices by 20 per cent on its top Claude AI model while claiming new safety safeguards make it the 'strongest-performing model we've tested', as the company faces intensifying competition from OpenAI and rising Chinese rivals.\n\nClaude Opus 5.5, launched on Tuesday, is the latest model in Anthropic's Opus line-up, above the mid-range Sonnet and cheaper Haiku tiers.\n\nThe San Francisco-based firm says the new model matches the performance of its top-tier Claude Fable 5.1 system on most tasks, at a fraction of the cost, while carrying safeguards previously reserved for its most advanced models in sensitive fields such as biology and cybersecurity.\n\n## Lower Prices Faster Output\n\nAnthropic cut list prices for Opus 5.5 by 20 per cent compared with Opus 5, to $4 per million input tokens and $20 per million output tokens. Cache reads, which make up the bulk of costs in coding and agent-based work, fell by 60 per cent to 20 cents per million tokens.\n\nOn typical workloads, Anthropic said total costs fall by around 40 per cent because the model completes tasks using fewer tokens and produces output more than 30 per cent faster than its predecessor. Claude Pro, Max and Team subscribers will also get longer usage limits, along with a rate-limit reset they can save and use when needed.\n\nAnthropic said Opus 5.5 outperformed OpenAI's GPT-5.6 Sol on a software-development benchmark while costing far less to run. In an internal trial, the company said, the model successfully found and fixed inefficiencies that cut page load times in 39 out of 40 runs.\n\n## New Safety Tests at Heart of Launch\n\nThe launch leans heavily on safety. Anthropic said its automated behavioural audit, which it calls its most comprehensive alignment test, gave Opus 5.5 the strongest results of any model the company has produced.\n\nThe firm said Opus 5.5 is markedly less likely than previous models to take hard-to-reverse actions or act outside agreed limits, and is more resistant to prompt injection than Opus 5.\n\nAccording to Anthropic's own figures, the model was around 85 per cent less likely than Opus 5 or Claude Mythos 5.1 to attempt to bypass containment boundaries in a dedicated evaluation.\n\nThe safety framing follows chief executive Dario Amodei's recent call for AI developers to 'pace the frontier' by slowing capability releases so that safety work can keep up. Writing earlier this month, Amodei said addressing the [risks of advanced AI](https://www.ibtimes.co.uk/anthropic-government-power-block-high-risk-ai-models-1819150) 'requires even more prudence'.\n\nAnthropic said Opus 5.5 was tested externally by independent groups Frontier Design and METR before release, in addition to its own alignment checks.\n\nBecause its biology and [cybersecurity capabilities](https://www.ibtimes.co.uk/anthropic-restricts-uk-access-claude-mythos-5-1-1818840) match those of Mythos 5.1 and Fable 5.1, the company said, Opus 5.5 is subject to the same restrictions, including limits on penetration testing and exploit generation, as well as safeguards around potentially dangerous biological research.\n\nAnthropic is also widening access to Opus 5.5 for vetted cybersecurity and life-sciences researchers through its verification programmes.\n\n## Raised Stakes Ahead of Possible IPO\n\nThe release comes as Anthropic prepares for a potential [initial public offering](https://www.ibtimes.co.uk/anthropic-ipo-ai-investment-1813702), with reports suggesting the company could seek a valuation approaching $2 trillion. The figure has not been confirmed by Anthropic.\n\nThe company was valued at $965 billion in its most recent private funding round. Anthropic's $65 billion Series H funding round in May gave it a post-money valuation of $965 billion.\n\nAnthropic faces growing competition from OpenAI, which has also cut prices in recent months, and from open-weight models built in China and elsewhere, which are increasingly run on customers' own hardware rather than through paid subscriptions.\n\nAnthropic said Sonnet 5.5 and Haiku 5.5 would follow in the coming weeks, with similar gains in performance, speed and safety.\n\n© Copyright IBTimes 2026. All rights reserved.", "url": "https://wpnews.pro/news/anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it", "canonical_source": "https://www.ibtimes.co.uk/anthropic-claude-opus-5-5-price-cut-safety-1821320", "published_at": "2026-09-22 19:07:28+00:00", "updated_at": "2026-09-22 19:23:57.419434+00:00", "lang": "en", "topics": ["large-language-models", "ai-safety", "ai-products", "ai-startups"], "entities": ["Anthropic", "Claude Opus 5.5", "Dario Amodei", "OpenAI", "GPT-5.6 Sol", "Claude Fable 5.1", "METR", "Frontier Design"], "alternates": {"html": "https://wpnews.pro/news/anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it", "markdown": "https://wpnews.pro/news/anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it.md", "text": "https://wpnews.pro/news/anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it.txt", "jsonld": "https://wpnews.pro/news/anthropic-calls-claude-opus-5-5-strongest-performing-model-we-ve-tested-as-it.jsonld"}}