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Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war

AchievementModelSep 22, 2026

OpenAI released GPT-6 Sol and GPT-6 Luna at half the price of their GPT-5.6 equivalents, with GPT-6 Luna at $0.10/$0.50 per million tokens. Anthropic's Claude Opus 5.5 received a 20% price cut to $4/$20 per million tokens, plus a 60% reduction in cache read pricing. However, Opus 5.5 at "max" thinking failed the author's pelican SVG test, hitting its 128,000 output token limit while reasoning.

Receipt № 20301 source · awaiting confirmation ◐

Evidence

1source· awaiting independent confirmation

No score is assigned. Sources and their independence are shown in the citation chain below.

Citation chain · 1 source

OpenAICompanyAnthropicCompanyGPT-5.6 SolModelGPT-5.6 TerraModelGPT-5.6 LunaModelGPT-6 SolModelGPT-6 LunaModelClaude Opus 5.5ModelGrok 4.7ModelMiMo v2.6 Flash/ProModelGPT-4.1 NanoModelGPT-5 NanoModel
Canonical: https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/