OpenAI and Anthropic release cheaper frontier models
OpenAI introduced GPT-6 Sol and Luna, while Anthropic released Claude Opus 5.5. OpenAI said Sol made roughly half as many mistakes as GPT-5.6 Sol and Luna matched that model's performance at about one per cent of the cost. Anthropic said Opus 5.5 delivered stronger performance at lower prices.
Why it matters
Lower model costs could broaden advanced AI use while keeping pressure on labs to improve reliability and safety.
Sources
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Part of the September 23, 2026 brief.