Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war
Why CEREBRO kept it
Opus 5.5 + GPT-6 model pricing tiers, direct token cost and model comparison data.
The text below is an automated extraction of the article at https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/, stored verbatim in the public cerebro-vault repository. Copyright remains with the original publisher (simonwillison.net).
<p>Yesterday was <a href="https://x.ai/news/grok-4-7">Grok 4.7</a> (<a href="https://news.ycombinator.com/item?id=49788838#49790209">pelicans</a>) and <a href="https://mimo.xiaomi.com/mimo-v2-6">MiMo v2.6 Flash/Pro</a> (<a href="https://news.ycombinator.com/item?id=49792730#49793480">more pelicans</a>). Today Anthropic <a href="https://www.anthropic.com/claude-opus-5-5">released Claude Opus 5.5</a>, and around an hour later OpenAI <a href="https://openai.com/index/introducing-gpt-6-sol-and-luna/">released GPT-6 Sol and GPT-6 Luna</a>. It's going to take a while to get a good read on all of the
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