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Beyond foundation models: October mega-rounds span the full AI infrastructure stack

We look into the tech companies that raised $100M+ rounds in October to uncover signals on market momentum, strategic plays, and the AI infrastructure stack. 

October’s record funding proves the AI infrastructure buildout remains far from over, with OpenAI’s $22.5B raise accounting for roughly half of the month’s total. 

However, unlike September’s concentrated focus on raw compute and model training, October’s AI infrastructure deals spread beyond models to encompass the full stack, from semiconductors to open-source databases.

This funding distribution presents a clear pattern: investors are backing companies that help businesses use AI, not just build it. This includes agent infrastructure, workflow automation, and verticalized AI tools for legal, healthcare, and industrial sectors.

Using CB Insights’ predictive signals, our monthly Book of Scouting Reports offers an in-depth analysis of every private tech company that has raised a funding round of $100M or more. It spotlights where private capital is concentrating, startups gaining momentum, and which companies are becoming tomorrow’s AI disruptors.

Download the book to see all 48 scouting reports.

October Mega-Rounds: Book of Scouting Reports

Get scouting reports on the companies that raised $100M+ rounds in October.

Key Takeaways

  • AI infrastructure funding is diversifying across the entire stack, from chips to agent frameworks. The 13 AI infrastructure companies that raised mega-rounds in October span semiconductors (Substrate, Tachyum, Nscale), models (OpenAI, Fireworks AI, xAI, Reflection AI, General Intuition, Fal), AI cloud computing (Crusoe), agent infrastructure (LangChain, n8n), and an open-source database (Supabase). Five of those companies — Fireworks AI, Substrate, LangChain, n8n, and Reflection AI — became unicorns (valuations of $1B+) this month. This breadth suggests that investors see additional opportunities across every layer of the infrastructure stack, rather than concentrating capital solely in categories with historically high funding, such as LLMs.
  • Legal AI companies are seeing the most momentum, outperforming even AI infrastructure (avg. Mosaic score of 840). The 3 legal AI companies that raised mega-rounds — Legora (Mosaic 847), Harvey (Mosaic 919), and EvenUp (Mosaic 803) — had the highest average Mosaic score (856) among October mega-rounds and span applications from personal injury claims to general legal workflows. Legal AI’s high Mosaic scores indicate strong potential for continued success, driven by existing tangible commercial traction: law firms and legal departments are already adopting these tools, as evidenced by Harvey’s reported $100M ARR. 
  • Healthcare companies are attracting $100M+ rounds despite early commercial maturity, signaling long-term bets on specialized AI. Healthcare companies averaged a Commercial Maturity score of 3 — the lowest of any major category across last month’s mega-rounds. These companies include Lila Sciences (Commercial Maturity score of 2: Validating), which integrates AI with autonomous laboratories for scientific discovery, and DUOS (Commercial Maturity score of 3: Deploying), which matches Medicare beneficiaries with resources using AI. Despite limited commercial traction, these companies raised substantial rounds showing investors are prioritizing long-horizon bets over near-term commercial validation.
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