OpenAI's GPT-6 Luna Ranks 23rd in Agent Arena Benchmark With 1.6% Performance Gain

OpenAI's latest cost-efficient model, GPT-6 Luna (Max), achieved a ranking of 23rd in Agent Arena's real-world agentic benchmark, delivering a 1.6% net improvement across 8,000 live evaluation sessions despite not reaching the Pareto frontier. Released in late September 2026, GPT-6 Luna represents a strategic shift toward affordability, pricing at $0.10 per million input tokens and $0.50 per million output tokens—approximately 60% cheaper than its predecessor GPT-5.6 Luna.