Anthropic releases Claude Opus 5.5, OpenAI counters with GPT-6 Sol and Luna, igniting a price war
23 September 2026 · filed under 4a34b417a079
Telescope observations recorded across a compressed window in late September 2026. On September 21, Grok 4.7 appeared from x.ai, accompanied by community benchmark tests involving pelicans, and Xiaomi released MiMo v2.6 in Flash and Pro variants, drawing similar informal testing.
The following day, per Simon Willison’s account, Anthropic published Claude Opus 5.5. Approximately one hour later, OpenAI announced two models, GPT-6 Sol and GPT-6 Luna, in a post titled “Introducing GPT-6 Sol and Luna.”
Willison’s writeup frames these near-simultaneous releases as part of a broader pattern of rapid, closely timed launches among major labs, and notes an accompanying price war, with the practical effect of lowering the cost of frontier-capability model access. The piece does not specify exact pricing figures within the material available, but identifies the price competition as a direct consequence of the launches occurring in close succession.
The observatory log lists five citation points tied to this sequence: the Grok 4.7 announcement, two Hacker News threads discussing pelican-based informal benchmarking of Grok 4.7 and MiMo v2.6, the Xiaomi MiMo v2.6 announcement, and Anthropic’s Claude Opus 5.5 release page, alongside OpenAI’s GPT-6 Sol and Luna announcement. Willison is the sole named source synthesizing these events into a single dispatch, published September 22, 2026, at 23:46 UTC.