AI
StepFun Launches Step 5 Preview: A 600B-Total, 27B-Active MoE Model With 1M Context for Long-Horizon Agentic Work
MarkTechPostMonday, September 21, 2026 at 6:37 AM
RedScroll Brief
StepFun has released Step 5 Preview, a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token. It supports a 1M-token context window and accepts text, image, and video input.
RedScroll Signal
- Impact
- High
- Category
- Ai
- Market relevance
- Moderate
- Why it matters
- AI developments move capital, regulation, and competitive advantage across the tech stack. StepFun has released Step 5 Preview, a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token. It supports a 1M-token context window and accepts text, image, and video input. Secondary effects may show up in markets and supply chains linked to Launches Step and Preview.
Desk copy
RedScroll Briefing
Extractive editorial brief — not a reprint of the original
What happened
StepFun has released Step 5 Preview, a sparse Mixture-of-Experts model with 600B total parameters and 27B active per token. It supports a 1M-token context window and accepts text, image, and video input.
Why it matters
AI developments move capital, regulation, and competitive advantage across the tech stack.
Background
MarkTechPost reported on this under ai. RedScroll surfaces the signal with an extractive brief — not a reprint of the original article. Read the source for full reporting.
Timeline
MarkTechPost published: StepFun Launches Step 5 Preview: A 600B-Total, 27B-Active MoE Model With 1M Context for Long-Horizon Agentic Work
Story is in today’s RedScroll edition. Follow the original source for updates.
Economic impact
Secondary effects may show up in markets and supply chains linked to Launches Step and Preview.
More on
Related stories
- Alibaba Qwen Releases Qwen3.8-Omni-Flash: A 1M-Context Omni-Modal Model Built Around Agentic Audio-Video Understanding and Tool Use
MarkTechPostAI
- How Cooley is accelerating IPO work with ChatGPT
OpenAI NewsAI
- Co-creating the future of fashion with Google
Google AI BlogAI
- Alibaba Qwen Team Releases Qwen3.8-LiveTranslate: A Real-Time Interpretation Model That Cuts Average Lag to 2.3 Seconds Across 60 Languages
MarkTechPostAI
- OpenClaw Releases 2026.9.5 With Atomic Updates, Plugin Hot Reload, Conversation Sharing, and Expanded GPT Live
MarkTechPostAI
- 4 ways to address the failures we found along the US border’s “virtual wall”
MIT Technology Review AIAI
Source
MarkTechPost
Original reporting by MarkTechPost. RedScroll provides an extractive briefing only.