Price war in AI: Anthropic launches Claude Opus 5.5, OpenAI responds with GPT-6

An hour apart, no more. Anthropic released Claude Opus 5.5 on Tuesday evening and OpenAI responded immediately with two GPT-6 models sold at half the price of their predecessors. The battle for artificial intelligence shifts to the price per million tokens, three weeks before Anthropic's IPO.

Claude Opus 5.5, the level of Fable 5.1 for 40% less

On paper, the technical sheet is enough to make developers salivate. Claude Opus 5.5 costs $4 per million tokens for input and $20 for output (one token is roughly three-quarters of a word), or 20% less than Opus 5. On a typical workload, Anthropic estimates the savings at 40%. Cache reads, those already processed instructions that the model reuses, drop 60% to 20 cents.

The laboratory claims to match Fable 5.1, its most powerful model, on most tasks. On Terminal-Bench 4.0, a standalone programming test, Opus 5.5 achieved 66.4% compared to 55.8% for Fable 5.1. One tester even completed the migration of 680,000 lines of code in less than a day. Text comes out 30% faster.

GPT-6 Sol and Luna, OpenAI’s response at knockdown prices

OpenAI did not wait until the next day. Built on the training methods of GPT-6 Astra, Sol and Luna are priced half as much as the GPT-5.6 versions of the same name. GPT-6 Sol increases to $2 per million tokens for entry and $10 for exit. Luna goes down to 10 and 50 cents, twenty times less than Sol.

OpenAI claims 68.8% for Sol on the DeepSWE software engineering test, 1.1 points behind Claude Fable 5, and an automation task completed for 27 cents on average. But don't look for a direct match. OpenAI compares itself to Fable 5.1 and Opus 5, Anthropic to its own models, and neither house has published a duel against the other's novelty.

AI price war, eyes on Wall Street

The calendar is no coincidence. Anthropic is preparing a listing on Nasdaq for mid-October, and OpenAI does not intend to let it have a monopoly on the good news. Lowering your prices just before going in front of investors means playing tight: the margin per request is falling, you will have to catch up on the volume.

For you, developer or business, this price war is timely. An agent that cost $100 per day on Opus 5 costs around $60 on Opus 5.5, for the same task according to Anthropic's figures. And on the crypto side, where agents are starting to pay for their own calls via payment protocols like x402, every cent withdrawn at the token price expands the scope of what standalone software can do profitably.