StepFun launches Step 5 Preview, a 600B MoE flagship model targeting coding and finance

Step 5 Preview: Advancing the Pareto Frontier

StepFun introduces Step 5 Preview, a 600B-parameter MoE model with 27B active per token, a 1M-token context window, and vision support. It scores 67.7 on DeepSWE v1.1, ahead of Kimi K3 and GLM-5.3 but behind GPT-6 Astra and Claude Opus 5. On the in-house StepCodeBench it hits 49.0, again leading domestic models and trailing the two US labs. On FrontierFinance it reaches 66.4, second only to Claude Opus 5. Artificial Analysis gives it an intelligence index of 44; StepFun claims substantially lower cost per task at comparable intelligence. The post does not disclose API pricing, release timeline, or training details.

Why it matters: StepFun's Step 5 Preview is a 600B MoE model that edges out Kimi K3 and GLM-5.3 on coding benchmarks but still trails GPT-6 Astra and Claude Opus 5 by 6-7 points. Scored 78 because it's a substantive domestic model push in agentic coding with real numbers, but not industry-sha...