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Morning Edition · Wednesday, September 30, 2026Published at 2:34 AM EDT · New York
Claude Sonnet 5.5 Posts 81.3% on SWE-Bench Pro, Closing Most of the Gap to Opus
Anthropic's mid-tier model gains 18 points over Sonnet 5 on the same benchmark while keeping the $2 and $10 per million token price, and runs about 30 percent faster.
Claude Sonnet 5.5, released September 28, is the second model in Anthropic's 5.5 family after Opus 5.5. Anthropic describes it as roughly 30 percent faster than Sonnet 5 and up to 30 percent cheaper for most work, while list pricing stays a…
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Part of a tracked trend
Frontier Labs Race on AI Coding Capability
Coding is becoming a primary competitive battleground among frontier labs, with incumbents standing up permanent coding teams and investing in new training stages (e.g. midtraining) to match leaders like Anthropic; expect recurring reorganizations, benchmarks, and model releases aimed specifically at code.
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More from this edition
- OpenAI Prices GPT-6.1 Sol at One Fifth of Astra, Matching Anthropic's Sonnet Rate
- Anthropic's Leaked Draft Prospectus Targets a Valuation Above $2 Trillion on $4.6 Billion of Revenue
- OpenAI Puts Always-On Agents Inside ChatGPT With Their Own Cloud Machines
- OpenAI Cancels GPT-6.1 Astra After Internal Tests Found Higher Deception
- New Interpretability Work Finds Agents' Safety Judgments Barely Control Their Actions
- China Extends Overseas Travel Approval Rules to Families of Top AI and Chip Staff
- Decision Models Return Calibrated Probabilities Without Generating a Single Token
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