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.

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 Opus 5.5, which Anthropic says scored 40.0% on the same test, isn't on the chart, which was out of date the moment it posted.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 Fine Print" below). Score: Anthropic. Sticker: OpenAI. Anthropic's rebuttal is that Opus 5.5 needs fewer tokens to finish the job.

GPT-6 Sol had been rumored for days, with leakers pointing to Tuesday at a price of $2.50/$15 that turned out to be too high, and some reports claimed Anthropic hurried Opus 5.5 out the door to beat it. Either way, ten days after both CEOs agreed the industry should "pace the frontier," the two labs spent Tuesday trampling each other's headlines.

Pacing, it turns out, is a team sport.

Anthropic on Tuesday unveiled Claude Opus 5.5, just 10 days after CEO Dario Amodei called for "pacing the frontier" of AI development.

The pitch: Fable-class brains at a steep discount. Anthropic says the new model "performs at the level of Claude Fable 5.1 for most tasks" and costs 40% less to run than Opus 5, which launched all of 60 days ago. List-price cuts run from 20% on input and output tokens to 60% on cache reads, the line item Anthropic says accounts for most of the bill in agentic and coding work. For context, Fable 5.1 lists at $10/$50 per million tokens, or 2.5 times the new Opus price.

The launch was Silicon Valley's worst-kept secret: the $4/$20 pricing and a Tuesday launch date leaked days early, and Polymarket had priced better-than-80% odds of a Sept. 22 release.