Update (1417ET): Well, well, well...
Anthropic's new Opus launch went up around lunchtime in New York, and by early afternoon OpenAI had rolled out GPT-6 Sol and GPT-6 Luna, halving prices yet again.
GPT-6 Sol now costs $2 per million input tokens and $10 per million output, half the $4/$20 promo rate Anthropic matched earlier today. GPT-6 Luna goes for a dime in and 50 cents out, pricing that looks built to fight the open-weight models eating token share. OpenAI says cached input gets a 90% discount, which puts Sol's cache reads at $0.20, the same rate we call Anthropic's "real knife" below. GPT-6 Astra stays on top at $10/$50. The upshot: the $4/$20 price point didn't survive the afternoon, and Opus 5.5 now costs twice as much as OpenAI's workhorse on input and output.
Higher usage limits and lower cost give you more flexibility and room to iterate. pic.twitter.com/AQJ5IlNsB1
— OpenAI (@OpenAI) September 22, 2026
OpenAI's charts, naturally, pit Sol against last-gen Claude. On AutomationBench, it touts Sol's 33.2% at 27 cents a task against Opus 5's 26.9% at 11 times the cost. Opus 5.5, which Anthropic says scored 40.0% on the same test, isn't on the chart, which was out of date the moment it posted. OpenAI also slipped in a dig at Anthropic's safeguards, noting in a footnote that Fable 5.1 fell back to Opus 5 on roughly 40% of tasks (see "The F
