Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war
Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war 22nd September 2026 Yesterday was Grok 4.7 (pelicans) and MiMo v2.6 Flash/Pro (more pelicans). Today Anthropic released Claude Opus 5.5, and around an hour later OpenAI released GPT-6 Sol and GPT-6 Luna. It’s going to take a while to get a good read on all of these new models, but here are my impressions so far.
- ▪Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war 22nd September 2026 Yesterday was Grok 4.7 (pelicans) and MiMo v2.6 Flash/Pro (more pelicans).
- ▪Today Anthropic released Claude Opus 5.5, and around an hour later OpenAI released GPT-6 Sol and GPT-6 Luna.
- ▪It’s going to take a while to get a good read on all of these new models, but here are my impressions so far.
Simon Willison files mainly under blogs. We currently carry 75 of its stories.
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| Original publisher | Simon Willison's Weblog |
| Canonical URL | https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/ |
| Publication time | 2026-09-22T23:46:41+00:00 |
| Retrieval time | 2026-09-23T00:30:03.548Z |
| Last seen | 2026-09-23T00:30:03.548Z |
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| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war 22nd September 2026 Yesterday was Grok 4.7 (pelicans) and MiMo v2.6 Flash/Pro (more pelicans). Today Anthropic released Claude Opus 5.5, and around an hour later OpenAI released GPT-6 Sol and GPT-6 Luna. It’s going to take a while to get a good read on all of these new models, but here are my impressions so far. GPT-6 Sol and Luna are half the price of their GPT-5.6 equivalents GPT-5.6 Luna was already my favorite model for building applications against, because it combined excellent performance with being really cheap. Somehow GPT-6 Luna is half the price of that again—and GPT-6 Sol had a similar reduction compared to GPT-5.6 Sol.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Simon Willison's Weblog.
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