StepFun Launches Step 5 Preview: 600B MoE with 27B Active, Open Weights on Oct 15
airesearch12 · x · 2026-09-20
StepFun officially introduced Step 5 Preview, its new flagship model for agentic work:
- Architecture: 600B total / 27B active MoE, 1M context with vision input
- Positioning: frontier-level performance in software engineering and professional knowledge work (notably finance), with sustained long-horizon execution
- Cost: substantially lower task cost at comparable intelligence; third-party commentary claims near GLM 5.3 / Kimi K3 quality for 65% cheaper
- Open weights: coming October 15
A direct challenge to leading closed models on agentic capability and price-performance from a Chinese lab.
Related event: StepFun Launches Step 5 Preview: 600B MoE Flagship, Open-Weights on Oct 15(17 posts)→
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