{"version":1,"type":"story","url":"https://digestai.news/story/stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and","json":"https://digestai.news/story/stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and.json","markdown":"https://digestai.news/story/stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and.md","slug":"stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and","headline":"StepFun releases Step 5 Preview open weights with 600B parameters and 1M context","summary":"StepFun has released Step 5 Preview as open weights on Hugging Face and ModelScope. The model is a sparse Mixture-of-Experts with 600B total parameters, 27B active per token, and up to 1M tokens of context. It is positioned for agentic work such as coding agents, document analysis, and finance workflows. The API launched September 20 and weights followed on October 14. StepFun reports the model scores 88.3% on AA-LCR long-context reasoning and 66.4% on FrontierFinance, while noting weaker performance on Terminal-Bench 4.0 at 33.3%. The FP8 checkpoint requires 4x B300 or 8x H200 GPUs, and the API charges $1.00 per 1M input tokens and $2.70 per 1M output tokens.","keyPoints":["Step 5 Preview has 600B total parameters, 27B active per token, and up to 1M-token context","API pricing is $1.00 per 1M input tokens and $2.70 per 1M output tokens","Best independent score is 88.3% on AA-LCR long-context reasoning"],"whyItMatters":"Step 5 Preview offers a new open-weight option for long-context agentic tasks, potentially lowering barriers for developers building self-hosted AI systems in coding, finance, and knowledge work.","category":{"slug":"models","name":"Generative AI & Models","url":"https://digestai.news/category/models"},"entities":{"companies":["StepFun"],"models":["Step 5 Preview"],"people":["Michal Sutter"]},"firstPublishedAt":"2026-10-17T06:29:55Z","updatedAt":"2026-10-17T06:29:55Z","sourceCount":1,"hasPrimarySource":false,"sources":[{"outlet":"MarkTechPost","title":"StepFun Releases Step 5 Preview Open Weights: 600B MoE, 27B Active, 1M Context","url":"https://marktechpost.com/2026/10/16/stepfun-releases-step-5-preview-open-weights-600b-moe-27b-active-1m-context","publishedAt":"2026-10-17T06:29:55Z","type":"press","primary":false,"lead":true}],"sourceNotes":null,"discussions":[],"thread":null,"cite":{"text":"Digest AI, \"StepFun releases Step 5 Preview open weights with 600B parameters and 1M context\", 17 October 2026, https://digestai.news/story/stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and","publisher":"Digest AI","title":"StepFun releases Step 5 Preview open weights with 600B parameters and 1M context","datePublished":"2026-10-17T06:29:55Z","url":"https://digestai.news/story/stepfun-releases-step-5-preview-open-weights-with-600b-parameters-and"},"generatedBy":"Written by Digest AI's editorial model from the linked sources; the sources are the record.","license":"Headlines, digests and key points are written by Digest AI and may be quoted with a link to the story page. Linked articles belong to their publishers. Terms: https://digestai.news/terms#reuse"}