OpenAI’s GPT-6 Sol (Max) achieves 7.7% net improvement while cutting API costs in half

OpenAI just made its most aggressive cost-performance play yet. GPT-6 Sol (Max), released on September 22, 2026, posted a +7.7% net improvement across more than 4,000 real-world agentic sessions on the Agent Arena leaderboard, while operating at roughly half the API cost of its predecessor. The model now sits at #6 on the leaderboard, up from the #8 spot held by GPT-5.6 Sol (xHigh), which managed only a +6.2% improvement. The numbers behind Sol’s leap GPT-6 Sol’s API pricing lands at $2 per million input tokens and $10 per million output tokens. That represents a 50% reduction from GPT-5.6 rates, a pricing move that transforms the economics of running agentic workflows at scale. On the Confirmed Success metric, which measures tasks definitively completed rather than partially attempted, GPT-6 Sol scored +11.4% and ranked #4 overall. That’s a stronger showing than its composite leaderboard position suggests, indicating the model is particularly reliable when tasks demand completion rather than approximation. On the DeepSWE v1.1 benchmark, a widely tracked measure of software engineering capability at maximum effort, GPT-6 Sol posted a score of 68.8%. That figure trails the top resul...