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.

Read original source → MARKTECHPOST Edition 2026-09-21

Desk copy

RedScroll Briefing

Extractive editorial brief — not a reprint of the original

What happened

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

Mon, Sep 21, 2026, 6:37 AM UTC
MarkTechPost published: StepFun Launches Step 5 Preview: A 600B-Total, 27B-Active MoE Model With 1M Context for Long-Horizon Agentic Work
Now
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.

Source

MarkTechPost

Original reporting by MarkTechPost. RedScroll provides an extractive briefing only.