OpenAI and Anthropic Roll Out Cheaper AI Models Amid Slowdown Debate

On Tuesday, Anthropic and OpenAI each introduced new AI models within a two-hour window, arriving just 10 days after both CEOs advocated for slowing AI development.

This time around, rather than unveiling their most advanced systems, both companies reduced pricing. Elon Musk, who also supported the slowdown call, offered congratulations to Anthropic.

Congrats!

— Elon Musk (@elonmusk) September 22, 2026

Anthropic Releases Opus 5.5 Following AI Slowdown Advocacy

Anthropic launched Claude Opus 5.5 at 16:31 UTC. According to the company, the system performs on par with Claude Fable 5.1 across most benchmarks while being 40% cheaper to operate compared to Opus 5.

Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family.

It performs at the level of Claude Fable 5.1 for most tasks, and costs 40% less to run than Opus 5. pic.twitter.com/Q9C2VKQ79f

— Claude (@claudeai) September 22, 2026

The 40% reduction is based on Anthropic's internal testing on standard workloads. Listed prices dropped 20%, settling at $4 per million input tokens and $20 per million output tokens. Tokens represent text segments that models process, with developers charged per token.

Opus 5.5 marks Anthropic's first release since CEO Dario Amodei published an essay on September 12 calling on AI labs to decelerate capability advancements. OpenAI's Sam Altman concurred, and Musk responded with “Dario is right,” as BeInCrypto reported.

Nevertheless, Amodei's essay did not call for a complete halt to releases.

“…pacing does not mean halting model training or technical progress, but ensuring companies take adequate time to align and safeguard their models,” wrote Amodei.

Anthropic stated that external evaluators METR and Frontier Design conducted reviews of Opus 5.5 prior to its release.

OpenAI Responds with Lower-Cost GPT-6 Sol and Luna

OpenAI unveiled GPT-6 Sol and GPT-6 Luna at 18:12 UTC. These two models are swifter and more affordable, built upon GPT-6 Astra, which retains its position as the company's flagship.

Please welcome GPT-6 Sol and GPT-6 Luna to the GPT-6 universe.

GPT-6 Sol and Luna build on the advances behind GPT-6 Astra, bringing much of its strengths into faster and more affordable models to support work at scale.

We’ve also made caching and inference more efficient, and… pic.twitter.com/5LiVE4rbFt

— OpenAI (@OpenAI) September 22, 2026

The firm cut prices in half for developers. Sol is priced at $2 per million input tokens, and Luna at $0.10. However, the 50% reduction is compared to GPT-5.6's promotional pricing rather than its standard rates.

Paying ChatGPT subscribers have access to both models starting today. Free-tier users can test Luna via the desktop application.

The slowdown commitment faced skepticism from the outset. Investor Michael Burry characterized it as self-serving IPO hype. Morgan Stanley, which serves as an underwriter for Anthropic's IPO, stated the initiative does not alter spending plans.

Neither company has announced a timeline for releasing a model that surpasses its current flagship.