Step 5 Preview: 600B-Parameter Model Pushes the Pareto Frontier in Coding and Finance

Step 5 Preview: Advancing the Pareto Frontier

StepFun's Step 5 Preview is a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token, featuring a 1M-token context window and vision input. It delivers frontier-level performance in software engineering and professional knowledge work, with particular strength in finance. On DeepSWE v1.1, it scores 67.7, just behind GPT-6 Astra (74.1) and Claude Opus 5 (74.0). It also excels in long-horizon tasks, optimizing an MLA GPU kernel to 508 TFLOPS in 22 hours and improving a post-training data loop to 60% on AIME24.