Arch Venture Partners
About Arch Venture Partners
ARCH began in 1986 as Arch Development Corporation, created at the University of Chicago. In 1992 Steven Lazarus and Booth School students Clint Bybee, Keith Crandell and Robert Nelsen left the university to run it as an independent firm. Headquarters are in Chicago, with offices in Seattle, San Francisco and Dublin. Nelsen and Crandell are co-founders and managing directors. Other managing directors named in third-party listings include Kristina Burow, Steve Gillis, Paul Berns and Mark McDonnell. Fund XII was $2.975 billion, announced in June 2022. Fund XIII closed in September 2024 with more than $3 billion. ARCH's own release says AI and new data-driven insights into biology are expected to help build a more preventive and curative healthcare system.
ARCH does not run a separate AI fund. Its AI work sits inside its main life science and technology funds. Nelsen is the partner most often tied to the largest AI deals. He led the initial investment in AI drug discovery company Xaira Therapeutics in 2024, and press reports name him among the first investors in Prometheus. In 2026 the firm led a $107M seed round in Trase, which builds agentic AI for regulated sectors. It also co-led a $75M Series A in Happy Health, an AI-enabled home care platform. The pattern is large early rounds in companies where AI is applied to biology, health, engineering or regulated industries. PitchBook describes Fund XIII as targeting biotechnology, healthcare, life science and AI.
ARCH invests mainly at seed and Series A, often in companies it co-founds with scientists, and it follows on in later rounds. It has not published check sizes. Third-party databases estimate initial checks at $500K to $5M, but treat that as an estimate. The 2026 rounds above show it will also lead or join much larger financings. Founders should expect introductions to run through a warm network, since the firm sources most companies itself.
- Prometheus: physical AI for engineering and manufacturing, co-led by Jeff Bezos. Crunchbase lists an ARCH round on 23 April 2026, and press reported a $12B raise in June 2026. Sources differ on the round size and on ARCH's role.
- Trase: agentic AI operating system for regulated sectors. $107M seed in June 2026, led by ARCH with Red Cell Partners.
- Syndex Bio: seed round of $15.5M listed on the Lounge deals desk, with Crunchbase showing a February 2026 round that included ARCH.
- Xaira Therapeutics: AI drug discovery company, backed in 2024 and listed among Fund XIII investments.
- Happy Health: AI-powered home-based care platform. $75M Series A in August 2026, led by ARCH and OpenLoop.
- en.wikipedia.org/wiki/Arch_Venture_Partners
- archventure.com/arch-venture-partners-announces-new-fund-xiii
- pitchbook.com/profiles/fund/25283-62F
- crunchbase.com/organization/arch-venture-partners/investor_summary/ove
- parsers.vc/fund/archventure.com
- fiercehealthcare.com/health-tech/fierce-healthcare-fundraising-tracker
- tsginvest.com/project-prometheus
- vcsheet.com/fund/arch-venture-partners
Investing activity
Arch Venture Partners appears in 3 AI deals tracked by the AI Lounge deals desk, rounds totalling $12.1B, and led 3 of them. The rounds are mostly Seed and Series B, with a median round size of $107M and the largest at $12B. The most recent are Trase (Seed, $107M, Jun 2026), Prometheus (Series B, $12B, Apr 2026) and Syndex Bio (Seed, $15.5M, Feb 2026).
Arch Venture Partners most often invests alongside Red Cell Partners, JPMorgan Chase, BlackRock and DST Global, and the companies it backs on AI Lounge are mostly in Service Industry, Physical AI / industrial and AI.
Deals
Frequently asked questions about Arch Venture Partners
Does Arch Venture Partners invest in AI startups?
Yes. Recent examples include Trase, Prometheus, Syndex Bio and Happy Health, plus Xaira Therapeutics in 2024. Most of its AI deals apply AI to biology, health, engineering or regulated industries.
How large are Arch Venture Partners' funds?
Fund XIII closed in September 2024 with more than $3 billion. It follows the $2.975 billion Fund XII announced in June 2022.
What check size does Arch Venture Partners write?
The firm has not published check sizes. Third-party databases estimate initial checks at $500K to $5M, and it has led much larger rounds such as Trase's $107M seed.
Who founded Arch Venture Partners?
Steven Lazarus, Clint Bybee, Keith Crandell and Robert Nelsen set it up as an independent firm in 1992. Its origins go back to Arch Development Corporation at the University of Chicago in 1986.
Which Arch Venture Partners partner should AI founders contact?
Robert Nelsen is the co-founder most often linked to its biggest AI deals, including Xaira. The firm favors warm introductions, and it does not publish a pitch process.
What AI companies has Arch Venture Partners invested in?
Arch Venture Partners's AI investments include Trase, Prometheus and Syndex Bio. The 3 rounds on AI Lounge are listed on this page with amounts, dates and co-investors.
Where is Arch Venture Partners based?
Arch Venture Partners is based in Chicago, US.
What stage does Arch Venture Partners invest at?
In the rounds tracked on AI Lounge, Arch Venture Partners has invested at Seed and Series B, with a median round of $107M. Arch Venture Partners led 3 of those rounds.
Who does Arch Venture Partners co-invest with?
Arch Venture Partners's most frequent co-investors on AI Lounge are Red Cell Partners (1 deal), JPMorgan Chase (1 deal), BlackRock (1 deal), DST Global (1 deal) and Goldman Sachs (1 deal).
How can founders reach Arch Venture Partners?
Founders on AI Lounge can see Arch Venture Partners's contact details in AI Investor Contacts (paid plans), check for a warm introduction through members who worked with the firm under Warm Paths, and add Arch Venture Partners to their Investor Pipeline to track the conversation.