OpenAI and Anthropic release cheaper AI models minutes apart amid intensifying price competition

On September 22, 2026, OpenAI and Anthropic launched cheaper, highly efficient versions of their flagship AI models within minutes of each other. OpenAI introduced GPT-6 Sol and GPT-6 Luna, slashing API prices by 50% compared to GPT-5.6 promotional rates. Anthropic debuted Claude Opus 5.5, reducing run costs by 40% compared to Opus 5. The dueling releases intensify an industry price war as corporate clients demand cost optimization, despite recent public calls by both companies' CEOs to pace frontier AI development.

New AI Model Releases

• ▪Anthropic plans to release Sonnet 5.5 and Haiku 5.5 in the coming weeks following the Claude Opus 5.5 launch.
• ▪Anthropic released Claude Opus 5.5 on September 22, 2026, as the first model in its new Claude 5.5 family.
• ▪OpenAI released GPT-6 Sol and GPT-6 Luna on September 22, 2026, as cheaper, faster offshoots of its flagship GPT-6 Astra model.

Pricing and Cost Reductions

• ▪OpenAI slashed API prices for GPT-6 Sol and GPT-6 Luna by 50% compared to GPT-5.6 promotional pricing.
• ▪OpenAI priced GPT-6 Sol at $2 per million input tokens and $10 per million output tokens, while GPT-6 Luna was priced at $0.10 input and $0.50 output per million tokens.
• ▪Anthropic priced Claude Opus 5.5 output tokens at $20 per million, representing an overall run-cost reduction of approximately 40% compared to Claude Opus 5.

Technical Drivers of Efficiency

• ▪Anthropic stated that Claude Opus 5.5 is faster to run and requires less compute than its predecessor, Claude Opus 5, due to token-efficiency innovations
• ▪OpenAI attributed the cost reductions of GPT-6 Sol and Luna compared to GPT-5.6 to improvements in caching and inference efficiency

Market Share and Revenue

• ▪Data from corporate expense platform Ramp showed OpenAI's GPT-6 Astra capturing 13% of monitored enterprise AI spending, compared to 8% for Anthropic's Claude Fable.
• ▪Anthropic's annualized revenue run rate surpassed $65 billion by late July 2026, while OpenAI's annualized revenue run rate crossed $40 billion in July 2026.

Calls for AI Slowdown

• ▪The September 22, 2026 releases of GPT-6 Sol, Luna, and Claude Opus 5.5 are the first from OpenAI and Anthropic since their respective CEOs called for an industrywide slowdown on advanced AI development
• ▪Anthropic CEO Dario Amodei published a blog post in mid-September 2026 outlining a plan for an AI slowdown, which OpenAI CEO Sam Altman supported in a post on X.

Model Safety and Evaluation

• ▪Anthropic applied the same cybersecurity, biology, and frontier-development safeguards to Claude Opus 5.5 that were previously reserved for Anthropic's Fable 5.1 model
• ▪Outside organizations METR and Frontier Design conducted pre-release evaluations and alignment testing on Anthropic's Claude Opus 5.5.