# The Rundown AI — Claude Sonnet 5.5 nears Opus ahead of OpenAI’s DevDay

- Company: The Rundown AI (therundown.ai)
- Announced: 2026-09-29T16:04:07.556000+00:00
- Category: new-model
- Coverage: not counted
- Announcement: yes
- Group: models
- Source: https://www.therundown.ai/news/claude-sonnet-5-5-nears-opus-devday
- Record: https://forck.live/items/15001-claude-sonnet-5-5-nears-opus-ahead-of-openai-s-devday
- Subject: Reporting
- Models affected: Claude Sonnet 5.5, Opus 5.5, Sonnet 5, GPT-6 Astra
- Pricing: Sonnet at $2 per million input tokens and $10 per million output tokens, compared with Opus's $4 and $20

Anthropic launched Claude Sonnet 5.5 on September 28, positioning it close to Opus 5.5 on several tests at half Opus's input and output token prices. At maximum effort, Artificial Analysis gave Sonnet 5.5 a score of 56 on its Intelligence Index, behind only Opus 5.5 at 58. Anthropic prices Sonnet at $2 per million input tokens and $10 per million output tokens, compared with Opus's $4 and $20, and claims output is at least 30% faster than Sonnet 5 with task costs up to 30% lower.

## Evidence

Verbatim from https://www.therundown.ai/news/claude-sonnet-5-5-nears-opus-devday:

> Anthropic launched Claude Sonnet 5.5 on September 28, putting its middle tier close to Opus 5.5 on several tests at half Opus's input and output token prices, as The Rundown reported .

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