Anthropic launched Claude Opus 5.5 on September 22, 2026 as the first model in its Claude 5.5 family, claiming it matches Claude Fable 5.1 performance while running 40% cheaper and 30% faster than Opus 5. The release highlights continued pressure on AI developers to improve efficiency without sacrificing quality.
The firm additionally claims the model posted the highest result ever seen on its most thorough internal alignment benchmark.
Anthropic presents Opus 5.5 as breaking the common pattern in which cost and latency reductions rely on distillation that trims capability.
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Anthropic released Claude Haiku 5.5, its cheapest and fastest small model, at $0.10 per million input tokens and $0.50 per million output tokens for prompts up to 100,000 tokens. Anthropic says it costs around 75% less to run than Haiku 4.5 on average and scores far higher on its benchmarks.
Anthropic has launched the Anthropic Cyber Mission to support defenders of critical infrastructure and open-source software with models, engineers, and tools. The initiative starts with the Critical Infrastructure Defense Program and free OSS Scanner amid ongoing challenges in verifying and fixing vulnerabilities.
OpenAI released 722 mathematical manuscripts, grouped into 372 result families, produced by an unreleased internal model. The papers are on GitHub, with Lean formalizations for many but not all of them, and OpenAI warns some unformalized results could have issues.
Meta and Microsoft are cutting employee use of Anthropic’s Claude AI and directing staff toward their own coding tools, The Information reported. The changes reflect tighter internal AI budgets while customer access to Claude through Microsoft platforms continues to expand.
Microsoft has introduced a local edition of MAI-Code-1.1-Flash that runs on Windows PCs without server access. The model requires substantial memory and is coming to GitHub Copilot in experimental preview by the end of October, starting with Nvidia RTX Spark PCs.
