Who founded Deep Fission?

Deep Fission was founded by Elizabeth A. Muller, Richard A. Muller in 2021.

Who are Deep Fission's investors?

Deep Fission's investors include Capital Factory, Deep Future, Stage 1 Ventures, Wave Function Ventures, 8VC, Blue Owl Capital.

How much funding has Deep Fission raised?

Deep Fission has disclosed $150M raised across 3 of its 4 known rounds.

Where is Deep Fission headquartered?

Deep Fission is headquartered in Berkeley, US.

Deep Fission

NASDAQ: FISN

Berkeley, US · Founded 2021 · Delaware corporation · 75 employees on LinkedIn · 8 known investors

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Deep Fission develops a nuclear reactor deployment system that places a pressurized water reactor about a mile underground in a deep borehole, using hydrostatic pressure for operating conditions and geothermal-style energy transfer to surface turbines. The company aims to reduce the cost and complexity of surface infrastructure and has signed letters of intent for power site partnerships totaling 18.5 GW.

Cleantech Deep Tech Energy

Founders & leadership

Deep Fission was founded in 2021 by Elizabeth A. Muller and Richard A. Muller.

Elizabeth A. Muller Co-Founder and CEO at Deep FissionElizabeth A. Muller is an Executive Officer and Director at Deep Fission, which develops pressurized water reactor systems deployed in deep boreholes. She also works on nuclear waste disposal at Deep Isolation.

Richard A. Muller FounderRichard Muller is a physicist who retired from UC Berkeley's faculty in 2010 and has served as CTO and cofounder of Deep Isolation, a nuclear waste isolation company, as well as cofounder and CTO of Deep Fission. He previously founded Berkeley Earth, a non-profit research organization focused on climate science, and holds over 30 patents in nuclear technology.

William Mark SchmitzChief Financial Officer

Michael Brasel Chief Operating OfficerMichael Brasel is Chief Operating Officer of Deep Fission and brings over 25 years of experience in nuclear and power plant operations. He serves on the boards of an electrical distribution company and a generation and transmission company, providing expertise in power markets and grid infrastructure.

Mark Pérès Chief Nuclear OfficerMark Pérès is Chief Nuclear Officer at Deep Fission and a PhD candidate in Nuclear Engineering at the University of South Carolina, where he teaches introduction to nuclear engineering. He brings 45 years of nuclear energy and facility experience, including prior roles as Vice President of Engineering at Kairos Power, Executive Project Director for Fluor's NuScale Power program, and leadership positions at the US DOE's Hanford Site managing spent nuclear fuel removal and reactor operations.

Stacy Tarver Patterson Chief Marketing OfficerStacy Tarver Patterson is Chief Marketing Officer at Deep Fission, which develops a nuclear reactor deployment system placed underground in deep boreholes. She previously held leadership roles at Nike (where she oversaw digital marketing across Greater China and direct-to-consumer strategy), Code and Theory, and West Ventures, and co-founded a venture-backed digital health company.

Elizabeth MullerFounder

Liz MullerFounder

Investors · 8

Capital Factorylisted by Capital FactoryAustin

How we know: Capital Factory's portfolio page · Not right? Tell us

Deep Futurelisted by Deep FutureSeattlevia Pablos Holman · inferred

How we know: Deep Future's portfolio page · the VCSheet dataset · open dataset · 5k.vc investor directory · Not right? Tell us

Stage 1 Ventureslisted by Stage 1 VenturesCoconut Grove

Wave Function Ventureslisted by Wave Function VenturesSeattle

8VCreportedAustin · $500K – $50M

How we know: the S-1 prospectus · Not right? Tell us

Blue Owl CapitalreportedNew York

How we know: funding news · Not right? Tell us

Also in the syndicate · 2

EE HoldingsMontrose Capital

Funding

SEC filings, press & company announcements

$150M disclosed across 3 of 4 rounds · 2025–2026

$40MraisedJun 2026
Source ↗

▶$80MraisedFeb 2026 · 223 investors · Other Energy

Rule 506(b)

Officers, directors & promoters on the filing

Jonathon AngellDirector
William Mark SchmitzExecutive Officer
Thomas S. GlanvilleDirector
Leslie Goldman TepperDirector
Jon GordonExecutive Officer
Elizabeth A. MullerExecutive Officer, Director
Michael BraselExecutive Officer
Richard MullerExecutive Officer
Blake JanoverDirector

Offering amount: $80M
Amount sold: $80M
Minimum investment: $10K
Sales commissions: $3.6M
Placement agents: The Benchmark Company, LLC, PHX Financial, Inc., d/b/a Phoenix Financial Services, Seaport Global Securities LLC, Network 1 Financial Securities, Inc.
First sale: Feb 2026
Incorporated: Corporation, Delaware, 2021
Federal exemptions: 06b

Full filing on SEC EDGAR ↗

▶$120MofferedSep 2025 · 83 investors · Other Energy

Rule 506(b)

Officers, directors & promoters on the filing

Elizabeth A. MullerExecutive Officer, Director
William Mark SchmitzExecutive Officer
Richard MullerExecutive Officer, Director

Offering amount: $120M
First sale: Sep 2025
Incorporated: Corporation, Delaware, 2021
Federal exemptions: 06b

Full filing on SEC EDGAR ↗

▶$30MraisedSep 2025 · 100 investors · Other Energy

Rule 506(b)

Officers, directors & promoters on the filing

Richard MullerExecutive Officer, Director
William Mark SchmitzExecutive Officer
Elizabeth A. MullerExecutive Officer, Director

Offering amount: $31.8M
Amount sold: $30M
Sales commissions: $2.1M
Placement agents: Seaport Global Securities LLC, Phoenix Financial Services, Network 1 Financial Securities, Inc., The Benchmark Company, LLC, Dinosaur Financial Group, L.L.C.
First sale: Sep 2025
Incorporated: Corporation, Delaware, 2021
Federal exemptions: 06b

Full filing on SEC EDGAR ↗

Source: SEC EDGAR Form D. Amounts as filed; amended filings shown once at their latest values.

Valuation · disclosed

Disclosed events

$965.3Mvaluation at IPOJun 2026 · $16.00/share · 424B4

filing ↗

Source: SEC prospectus filings, and round valuations the company or its investors disclosed — follow each entry's link for the claim.

Founder mafia

4 people who came through Deep Fission went on to found or lead other companies.

Stuart LaceyChief AI StrategistFounded Trunomi +1 Joanna RileyInvestor & AdvisorFounded Censia Richard MullerFounderFounded Deep Isolation Elizabeth A. MullerExecutive Officer, DirectorFounded Deep Isolation

In the news

Deep Fission Advanced Nuclear Raises $80 Million in Financing to Accelerate Commercialization :: Deep Fission, Inc. (FISN)deepfission.com · Feb 2026

Frequently asked questions

What does Deep Fission do?: Deep Fission develops a nuclear reactor deployment system that places a pressurized water reactor about a mile underground in a deep borehole, using hydrostatic pressure for operating conditions and geothermal-style energy transfer to surface turbines. The company aims to reduce the cost and complexity of surface infrastructure and has signed letters of intent for power site partnerships totaling 18.5 GW.
Who founded Deep Fission?: Deep Fission was founded by Elizabeth A. Muller, Richard A. Muller in 2021.
Who are Deep Fission's investors?: Deep Fission's investors include Capital Factory, Deep Future, Stage 1 Ventures, Wave Function Ventures, 8VC, Blue Owl Capital.
How much funding has Deep Fission raised?: Deep Fission has disclosed $150M raised across 3 of its 4 known rounds.
Where is Deep Fission headquartered?: Deep Fission is headquartered in Berkeley, US.