{"slug": "stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15", "title": "StepFun teases Step 5 Preview, a 600B/27B MoE, open weights coming Oct 15", "summary": "StepFun announced Step 5 Preview, a 600B total / 27B active mixture-of-experts flagship model for agentic work with 1M context and vision, and said open weights will be released on Oct 15. StepFun claims the model delivers frontier-level performance across software engineering and professional knowledge work, with particular strength in finance, at substantially lower task cost at comparable intelligence. The company cited one agent action that coordinated 950 web fetches and said the model sustains execution over long horizons across software environments, web applications, 3D workflows and programmable hardware.", "body_md": "StepFun on X: \"Introducing Step 5 Preview: Advancing the Pareto Frontier.\nStep 5 Preview is our new flagship model for agentic work, delivering frontier-level performance across software engineering and professional knowledge work, with particular strength in finance.\n- 600B total / 27B active Mo… / X\n\nStepFun on X: \"Introducing Step 5 Preview: Advancing the Pareto Frontier.\nStep 5 Preview is our new flagship model for agentic work, delivering frontier-level performance across software engineering and professional knowledge work, with particular strength in finance.\n- 600B total / 27B active MoE, with 1M context + Vision\n- Substantially lower task cost at comparable intelligence\n- Broad software engineering capabilities with sustained execution over long horizons\nTry Step 5 Preview: https://t.co/fC7HHlWKFn\nModel page: https://t.co/4caJR2YGD3\nOpen weights on Oct 15.\"\n\nIntroducing Step 5 Preview: Advancing the Pareto Frontier.\nStep 5 Preview is our new flagship model for agentic work, delivering frontier-level performance across software engineering and professional knowledge work, with particular strength in finance.\n- 600B total / 27B active MoE, with 1M context + Vision\n- Substantially lower task cost at comparable intelligence\n- Broad software engineering capabilities with sustained execution over long horizons\nTry Step 5 Preview: platform.stepfun.ai\nModel page: stepfun.com/step-5-preview\nOpen weights on Oct 15.\n\nIntroducing Step 5 Preview: Advancing the Pareto Frontier.\nStep 5 Preview is our new flagship model for agentic work, delivering frontier-level performance across software engineering and professional knowledge work, with particular strength in finance.\n- 600B total / 27B active MoE, with 1M context + Vision\n- Substantially lower task cost at comparable intelligence\n- Broad software engineering capabilities with sustained execution over long horizons\nTry Step 5 Preview: platform.stepfun.ai\nModel page: stepfun.com/step-5-preview\nOpen weights on Oct 15.\n\nStep 5 Preview works across software environments and sustains execution over long horizons.\nIts capabilities extend from software engineering and web applications to 3D workflows and programmable hardware.\nOver longer horizons, Step 5 Preview keeps track of prior results, usesShow more\n\nStep 5 Preview is built for professional knowledge work — from large-scale research to structured analysis and interactive reporting.\nIt coordinates research at scale and turns evidence into finished, auditable deliverables. In one agent action, it coordinated 950 web fetchesShow more\n\nFinance is a particular focus for Step 5 Preview.\nFinancial work has to stand up to scrutiny. We evaluate Step 5 Preview on its ability to identify and verify reliable information, reconcile differences across reports, make assumptions explicit, and produce internally consistentShow more", "url": "https://wpnews.pro/news/stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15", "canonical_source": "https://twitter.com/StepFun_ai/status/2101510462685003786", "published_at": "2026-09-22 05:06:48+00:00", "updated_at": "2026-09-22 05:25:03.262510+00:00", "lang": "en", "topics": ["large-language-models", "ai-agents", "ai-products", "generative-ai", "ai-startups"], "entities": ["StepFun", "Step 5 Preview", "platform.stepfun.ai", "stepfun.com"], "alternates": {"html": "https://wpnews.pro/news/stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15", "markdown": "https://wpnews.pro/news/stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15.md", "text": "https://wpnews.pro/news/stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15.txt", "jsonld": "https://wpnews.pro/news/stepfun-teases-step-5-preview-a-600b-27b-moe-open-weights-coming-oct-15.jsonld"}}