OpenAI and Anthropic Slash Prices Within 90 Minutes, Kicking Off a New Model Price War

On September 23, OpenAI and Anthropic released cheaper models within about 90 minutes of each other, kicking off a new API price war. OpenAI cut GPT-6 Sol and Luna API prices by 50% versus GPT-5.6 promotional pricing, while Anthropic launched Claude Opus 5.5 at roughly 40% lower prices. Observers see model competition shifting from intelligence to cost efficiency.

Confirmed

GPT-6 Sol is priced at $2/M input and $10/M output, about one-fifth of 5.6-Sol pricing, in line with Terra 5.6 and Sonnet 5 (@TraditionalHome8852, @haider1)
GPT-6 Luna is priced at $0.10/M input and $0.50/M output; even the already-cheap 5.6-Luna looks expensive by comparison (@altryne, @haider1)
Anthropic released Claude Opus 5.5, claiming it is about 40% cheaper (@krishnan)
Simon Willison reviewed Claude Opus 5.5 and GPT-6 Sol/Luna the same day, flagging the new price war (via @altryne)

Interpretations

@TansuYegen argues that both companies suddenly competing hard on cost, not just intelligence, is usually a sign of technology moving from impressive to genuinely useful at scale
@krishnan observes model pricing shifting toward "per-task accounting"
@bindureddy says the simultaneous price cuts show open-source models are putting real pressure on closed vendors
@TraditionalHome8852 reasons that since OpenAI did not release GPT-6 Terra, Sol's real target is the upcoming Sonnet 5.5 rather than Opus
@haider1 calls the pricing "ridiculously good" and says OpenAI has changed the game on price-performance

Unconfirmed

Reddit user @JPBartley asks whether, given both companies were reportedly losing money before the cuts, further price cuts are about market share or a sustainable business—an open question

Why it matters

The price war shifts competition from pure intelligence to cost efficiency and could accelerate large-scale AI adoption, though sustainability of the losses remains uncertain

2026-09-23 ~ 2026-09-25 · 7 related posts

Full story(8 episodes)→

Episode 1: OpenAI Launches GPT-6 Sol and Luna at Half Price; Big Hallucination Gains but Not a Clean Sweep(2026-09-23, 92 posts)
Episode 2: GPT-6 Sol/Luna launch splits opinion: half-price but dumber?(2026-09-23, 9 posts)
Episode 3: LMArena Opens GPT-6 Sol and Luna for Public Testing(2026-09-23, 2 posts)
Episode 4: Four New Models Reshape the Cost-Performance Frontier, Opus 5.5 Tops Intelligence Index(2026-09-23, 2 posts)
Episode 5: OpenAI and Anthropic Slash Prices Within 90 Minutes, Kicking Off a New Model Price War(2026-09-23, 7 posts)
Episode 6: Tests Show GPT-6 Sol Scales Nearly Linearly With Effort(2026-09-23, 3 posts)
Episode 7: Leaks Map GPT-6 Codenames to GPT-5.6 Versions(2026-09-24, 3 posts)
Episode 8: OpenAI's efficient GPT-6 models seen as freeing compute for bigger frontier models(2026-09-25, 2 posts)

Primary sources

OpenAI cuts API prices 50%, Opus 5.5 runs 40% cheaper: model pricing shifts to cost per task — krishnan · 2026-09-25 08:44 (UTC+08:00)
GPT-6 Luna priced at $0.10/$0.50, half of GPT-5.6, as Anthropic and OpenAI spark a price war — altryne · 2026-09-23 14:56 (UTC+08:00)
GPT-6 Sol and Luna Pricing Slashes Costs: Sol at One-Fifth of 5.6-Sol — haider1 · 2026-09-23 18:50 (UTC+08:00)

GPT-6 Sol's price cut means it should be compared to Sonnet, not Opus — TraditionalHome8852 · 2026-09-23
[source] GPT-6 Luna priced at $0.10/$0.50, half of GPT-5.6, as Anthropic and OpenAI spark a price war — altryne · 2026-09-23
Anthropic and OpenAI now competing hard on cost, not just intelligence — TansuYegen · 2026-09-23
Anthropic and OpenAI price cuts show open-source models are winning — bindureddy · 2026-09-23
[source] GPT-6 Sol and Luna Pricing Slashes Costs: Sol at One-Fifth of 5.6-Sol — haider1 · 2026-09-23
Are OpenAI and Anthropic actually making money after their latest price cuts? — JPBartley · 2026-09-24
[source] OpenAI cuts API prices 50%, Opus 5.5 runs 40% cheaper: model pricing shifts to cost per task — krishnan · 2026-09-25