Deep Fission
NASDAQ: FISNBerkeley, US · Founded 2021 · Delaware corporation · 75 employees on LinkedIn · 7 known investors
Find your way into Deep Fission
239 people in our graph share verified history with the Deep Fission team — schools, employers, funds. One of them is your warm intro.
Jessy Rivestunlockedknows Richard Muller · together at Lawrence Berkeley National Labs (overlapped)
×3knows the team · via UC San Diego
×6knows the team · via Lawrence Berkeley National Labs
×2knows the team · via ESCP
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.
Founders & leadership
Deep Fission was founded in 2021 by Richard Muller, Elizabeth A. Muller, and Richard A. Muller.
RM
Richard MullerinCo-founderRichard Muller is a former professor of physics who co-founded Berkeley Earth, a climate science non-profit, and previously served as CTO and co-founder of Deep Isolation, a nuclear waste disposal company. He is currently CTO and co-founder of Deep Fission, which develops underground nuclear reactor systems.
EA
Elizabeth A. MullerinCo-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.
RA
Richard A. MullerinChief Technology OfficerRichard 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.
WM
William Mark SchmitzChief Financial Officer
MB
Michael BraselinChief 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.
MP
Mark PérèsinChief 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.
ST
Stacy Tarver PattersoninChief 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.
Investors · 7
Capital FactoryAustin
Stage 1 VenturesCoconut Grove
8VCreportedAustin · $100K – $50M
Blue Owl CapitalreportedNew York
Deep FuturereportedSeattlevia Pablos Holman · inferred
Also in the syndicate · 2
EE HoldingsMontrose Capital
Funding
SEC filings, press & company announcements$150M disclosed across 3 of 4 rounds · 2025–2026
- $40MraisedJun 2026Source ↗
▶$80MraisedFeb 2026 · 223 investors · Other EnergyRule 506(b)
▶$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
▶$120MofferedSep 2025 · 83 investors · Other EnergyRule 506(b)
▶$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
▶$30MraisedSep 2025 · 100 investors · Other EnergyRule 506(b)
▶$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
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
3 people who came through Deep Fission went on to found or lead other companies.
In the news
🌎 Micro-reactor funding goes macro #309ctvc.co · Aug 2026Frequently 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 Richard Muller, Elizabeth A. Muller, Richard A. Muller in 2021.
- Who are Deep Fission's investors?
- Deep Fission's investors include Capital Factory, Stage 1 Ventures, 8VC, Blue Owl Capital, Deep Future.
- 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.