StepFun's Step 5 Preview scores 44 on Intelligence Index at lower cost

StepFun's Step 5 Preview scores 44 on the Artificial Analysis Intelligence Index at about $0.72 per task, matching Kimi K3 (max) at roughly 2.8x lower cost. The source reports strong reasoning results, including 46% on Humanity's Last Exam, but places it behind Qwen3.8 Max and GLM-5.3 (max) on agentic evaluations. Open weights are planned for October 15.