Marathon Fusion
marathonfusion.com
Nuclear Energy
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Overview
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News
Salaries
Products
People
Growth
Offices
Financials
Funding and backers
Total raised
$5M
1 round on record
Latest round
$5M
Convertible Note · Dec 2022 · 3 yr ago
Team
22
US Form 5500 (plan participants) · Dec 2025
Backers
2
Earthrise Ventures, Übermorgen Ventures
The money's age
Long since its last round
46 months since the last round · not hiring
Momentum
15/100
in the news
Last sign of life
1 mo ago
a posting or a news item
The story so fareach stage dated by its source: the company's releases, the press, registers, filings
Tractionpublic signals, read monthly
Web presence
top 6%
of 133.2M domains by links, Common Crawl
Hacker News stories
2
best: 65 points
Funding rounds
| Round | Date | Amount | Investors | Source |
|---|---|---|---|---|
| Convertible Note | Dec 2022 | $5M | — | SEC Form D |
Registers and programsofficial lists and records that name the company
| Legal entity | Marathon Fusion, Inc. | SEC Form D |
Founders and leadersfrom filings, registers and the company's site
Adam RutkowskiExecutive Officer, DirectorSEC Form D
Kyle SchillerExecutive Officer, DirectorSEC Form D
Backed byfrom the funds' portfolios and accelerator catalogs
Investors in similar startupsfunds that back the companies most like this one
Similar startupsby what they do, their industry and backers
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Visa sponsorship
3
H-1B filings in 12 months
$168k
Median offered salary
0
Open roles in United States
Who they sponsor
Materials scientists
1
Physicists
1
Data scientists
1
In the register as Marathon Fusion, Inc., San Francisco, CA
Other sponsors in the same field
AtkinsRéalis 
GE Vernova 
Dominion Energy 
Day & Zimmermann
Alert me
US Department of Labor · latest filing Apr 6, 2026 · Visa details by country
Overview
Marathon Fusion develops fuel cycle technology for fusion power plants, particularly systems that separate and recycle hydrogen isotopes. Fusion developers need tritium handled at high throughput, a problem largely unsolved outside national laboratories. The company builds hardware for reactor developers rather than a reactor of its own.
Connections
List
Graph
Found in company registers, site code, DNS and hiring. Each connection shows how sure we are and the evidence, with its source and date.
Shared investors
Übermorgen VenturesVia a fund
26 portfolio companies: Zymvol, This website is administered by Visionaries Club GmbH, Verna and 23 more
Earthrise VenturesVia a fund
Click a company to open it. Dashed lines are likely connections. The second step of the network is part of the Pro plan.
Owner
Same company
Same group
Likely
News
Exclusive: Marathon Fusion Achieves Reactor Fuel Breakthrough
The seed-stage startup is eyeing a Series A after successfully enriching lithium and hydrogen isotopes.
Read more
Report
An Unusual Way to End Up With a Whole Lot of Gold
In the 21st century, the dream of alchemy is not just alive but atomic.
Read more
Report
Report
People
Adam Rutkowski
Executive Officer, Director
Kyle Schiller
Executive Officer, Director
Names and roles come from public filings, company registers and the company's own site. Is this you? Correct or remove · How we handle this data
Offices
Where the company hires and what each office is for
Cities
1
Hiring now
0
Countries
1
San Francisco
United States
HQ
Industrial-scale isotope production for critical industries
150 Mississippi Street, San Francisco, CA 94107
Financials
Total raised
$5M
Latest round
Convertible Note
Funding rounds
1
Funding rounds
| Round | Announced | Amount | |
|---|---|---|---|
| Convertible Note | 2022 | $5M | Details |