OpenAI’s September 2026 GPT-6 family launch set the current frontier benchmark with GPT-6 Astra priced at $50 per million output tokens, alongside GPT-6.1 Sol at $10 and GPT-6 Luna at $0.50, reflecting inference optimizations and improved caching that cut prior GPT-5.6 rates by roughly half while preserving or advancing capabilities on agentic and reasoning benchmarks. This pricing aligns closely with Anthropic’s Claude Fable 5.1 at the same flagship level and undercuts Google’s introductory Gemini 4 Argon rates, intensifying tiered competition. Traders monitor the November 21 expiration of GPT-5.6 Sol’s promotional pricing and any year-end model updates, as further efficiency gains or rival moves could pressure the top-tier output rate lower before year-end amid ongoing cost declines across the frontier index.