---
format: "aidr-story-markdown/v1"
id: "04d48b78906706c989ec977de29df83cca2ec4b69acf6bedd24bb82a44d3a812"
canonical_url: "https://aidr.today/04d48b78?lang=en"
title: "StepFun Opens 600B Parameter Step 5 Preview as Open Weights Flagship"
lang: "en"
requested_lang: "en"
available_langs: ["en","vi"]
translation_fallback: null
fallback_fields: []
published_at: "2026-10-15T13:24:44.000Z"
category: "Open Source"
topics: ["llm","open-source"]
source_urls: ["https://marketbrief.now/ai/stepfun-opens-600b-parameter-step-5-preview-as-open-weights-flagship-fcb3f690","https://x.com/StepFun_ai/status/2110717330657616092","https://x.com/AdinaYakup/status/2110689169848647834","https://x.com/sgl_project/status/2110717632257155164","https://x.com/vllm_project/status/2110719689127292945","https://x.com/vllm_project/status/2110719764771537370","https://huggingnews.com/ai/stepfun-opens-600b-parameter-step-5-preview-as-open-weights-flagship-fcb3f690","https://www.marktechpost.com/2026/10/16/stepfun-releases-step-5-preview-open-weights-600b-moe-27b-active-1m-context/"]
summary: "StepFun released Step 5 Preview, a 600 billion parameter open-weights AI model using a sparse Mixture of Experts architecture, available on Hugging Face and ModelScope with support from vLLM and SGLang."
---

# StepFun Opens 600B Parameter Step 5 Preview as Open Weights Flagship

> [Open the canonical story](<https://aidr.today/04d48b78?lang=en>)

**Published:** 2026-10-15T13:24:44.000Z
**Category:** Open Source
**Topics:** llm, open\-source

## Summary

StepFun released Step 5 Preview, a 600 billion parameter open\-weights AI model using a sparse Mixture of Experts architecture, available on Hugging Face and ModelScope with support from vLLM and SGLang\.

## Sources

- [Story source](<https://marketbrief.now/ai/stepfun-opens-600b-parameter-step-5-preview-as-open-weights-flagship-fcb3f690>)
- [Story source](<https://x.com/StepFun_ai/status/2110717330657616092>)
- [Supporting source](<https://x.com/AdinaYakup/status/2110689169848647834>)
- [Supporting source](<https://x.com/sgl_project/status/2110717632257155164>)
- [Supporting source](<https://x.com/vllm_project/status/2110719689127292945>)
- [Supporting source](<https://x.com/vllm_project/status/2110719764771537370>)
- [Story source](<https://huggingnews.com/ai/stepfun-opens-600b-parameter-step-5-preview-as-open-weights-flagship-fcb3f690>)
- [Story source](<https://www.marktechpost.com/2026/10/16/stepfun-releases-step-5-preview-open-weights-600b-moe-27b-active-1m-context/>)