GPT-6 Sol

Anthropic released Claude Opus 5.5, claiming roughly 40% lower running costs than Opus 5, while OpenAI introduced GPT-6 Sol and GPT-6 Luna with API prices cut 50% from GPT-5.6 promotional rates. The releases mark the first launches from either lab since Anthropic CEO Dario Amodei called for an industry slowdown on advanced AI development.

Anthropic released Claude Opus 5.5 at $4/$20 per million input/output tokens, undercutting Opus 5's $5/$25 pricing while claiming better agentic coding scores. OpenAI countered with GPT-6 Sol ($2/$10) and GPT-6 Luna ($0.10/$0.50), both up to 50% cheaper than GPT-5.6's promotional rates.

OpenAI has released GPT-6 Sol Pro, which runs the existing GPT-6 Sol model with its reasoning mode set to 'pro' for higher-quality responses on complex tasks. It carries a 1.1 million token context window and is priced at $2 per 1M input tokens and $10 per 1M output tokens.

OpenAI has released GPT-6 Sol and Luna, updated versions of its mid-tier and lightweight models, priced at half the cost of their GPT-5.6 predecessors. The company claims GPT-6 Sol makes roughly half as many factual errors as its predecessor, reaching what it calls 'Astra-level reliability' at lower cost.