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Marathon Fusion

High-throughput fusion fuel recycling system

Overview

Company Does Not Provide H-1B Sponsorship

Marathon Fusion develops fuel-cycle technologies for fusion energy, building a high-throughput system that recycles fusion fuel (deuterium and tritium) with metal foil pumps using hydrogen superpermeation. Its product continuously processes and recycles fuel, lowering the tritium inventory plants must store and reducing operating costs, which can enable smaller, cheaper fusion plants. It differentiates itself by focusing on fuel-cycle hardware and pursuing additional revenue streams from material production, including a proposed scalable nuclear transmutation that could produce gold and other isotopes. Its goal is to accelerate the deployment of commercial fusion by improving fuel efficiency and economics while expanding revenue opportunities.

Significant Headcount Growth

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About Marathon Fusion

Simplify's Rating
Why Marathon Fusion is rated
C+
Rated B on Competitive Edge
Rated C on Growth Potential
Rated C on Differentiation

Industries

Industrial & ManufacturingEnergy

Company Size

11-50

Company Stage

Grant

Total Funding

$9.9M

Headquarters

San Francisco, CA

Founded

2023

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Simplify's take

What believers are saying

  • September 3, 2026 reporting says Marathon is building its first commercial pilot facility.
  • July 2024 LOIs with Commonwealth Fusion Systems and Helion Energy anchor early customer pull.
  • October 2026 hiring and SF office expansion signal execution momentum and technical scaling.

What critics are saying

  • October 21, 2026 gold claims lack independent verification, disclosed yield, and cost data.
  • Commercial success depends on fusion plants that do not exist; revenue timing slips beyond 2029.
  • A failed pilot would strand Marathon as a niche materials vendor with no reactor customers.

What makes Marathon Fusion unique

  • Marathon Fusion targets fuel-cycle infrastructure, not electricity generation, with isotope-processing hardware.
  • Its plasma centrifuge links tritium recycling, lithium enrichment, and radiopharma isotope production.
  • ARPA-E VISION OPEN backs Marathon through March 2029, validating its specialized fusion supply-chain niche.

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Funding

Total Funding

$9.9M

Above

Industry Average

Funded Over

2 Rounds

Grant funding comparison data is currently unavailable. We're working to provide this information soon!
Grant Funding Comparison Coming Soon

Benefits

  • Health Insurance
  • Dental Insurance
  • Unlimited Paid Time Off
  • 401(k) Retirement Plan
  • Commuter Benefits
  • Company Equity

Growth & Insights and Company News

6 month growth

6%

1 year growth

0%

2 year growth

21%
Open KG
Oct 23rd, 2026
Can artificial gold lead to a price collapse, as happened with diamonds?

Can artificial gold lead to a price collapse, as happened with diamonds? Сергей Гармаш - 23.10.2026, 17:55 - Exclusive Новости Кыргызстана События сегодня Новости Бишкека The San Francisco startup Marathon Fusion has announced a significant breakthrough in the field of transmutation, successfully converting mercury into stable gold ten times faster than CERN. This discovery raises an important question about the potential impact of lab-produced gold on the precious metals market, causing concern in the jewelry industry. On Wednesday, Marathon Fusion confirmed that it achieved transmutation last month, marking a significant achievement in the field of nuclear fusion energy. Founded in 2023, the organization is developing technologies for future nuclear fusion power plants that could generate electricity similarly to the processes occurring in the Sun. So far, the claimed results have not been verified by independent experts; however, they revive the dreams of alchemists and could lead to changes in the jewelry industry, similar to how lab-grown gemstones have impacted the diamond market. Marathon Fusion collaborates with the U.S. Department of Energy and has been awarded the ARPA-E prize for its high-risk energy research. Among the company's investors are Breakthrough Energy, a Bill Gates initiative, and the mining company Anglo American, known for its natural diamonds. According to the company, they were able to convert mercury into stable gold, significantly surpassing CERN's previous achievements, which produced gold in negligible quantities. CERN previously reported that its Large Hadron Collider produced only a small amount of gold, which existed for a very short time. The method used by Marathon involves the use of neutrons to transmute mercury, allowing for the production of gold. The company also claims to have surpassed the Soviet record by using its plasma centrifuge, which separates isotopes for nuclear fuel. A reactor promising record power density is currently under construction in San Francisco. While the discovery requires independent verification, it raises interest in how lab-made gold could impact the market, especially in light of the experience with lab-grown diamonds. Impact of lab-grown stones on the market. Lab-grown diamonds have the same chemical structure as natural ones, but their mass production has led to a significant drop in market prices. Experts note that wholesale prices for such stones have fallen by 90-95% since 2015, which has also affected the prices of natural diamonds. De Beers, one of the leading diamond producers, launched a brand of lab-grown stones but ultimately closed it, focusing instead on natural diamonds. This illustrates how quickly the market can change in response to new technologies. Gold: situation and prospects. The gold market is much larger, with production of about 3,672 tons just in 2025. Central banks are also actively buying gold as a means of preserving value, adding stability to this market. Marathon Fusion suggests that nuclear fusion power plants could produce significant volumes of gold; however, no such plants are currently operating on a commercial scale. Additionally, transmuted gold may contain radioactive isotopes that would require time for safe market implementation. While plans for the commercialization of such gold are not yet defined, its uniqueness and potential market impact remain subjects of discussion within the community. Новости Оша Экономические новости Общество новости

The Deep Dive
Oct 22nd, 2026
Marathon Fusion claims 10x CERN gold record without disclosing actual yield.

Marathon Fusion claims 10x CERN gold record without disclosing actual yield. Marathon Fusion says its laboratory experiment beat CERN's gold-production benchmark by a factor of 10, but the company has yet to disclose how much gold it actually made. The San Francisco startup announced on Wednesday that it had converted mercury into stable gold using fusion neutrons during an experiment the previous month. It also reported producing radioactive copper isotopes from zinc. Both are company-reported results, with no independently validated experimental yield available in the material reviewed. CERN provided a more explicit comparison in May 2025. Its ALICE collaboration measured a maximum production rate of approximately 89,000 gold nuclei per second during lead-ion collisions. Across four Large Hadron Collider experiments between 2015 and 2018, an estimated 86 billion gold nuclei were produced, equivalent to just 29 picograms. Sponsored · Selkirk Copper Mines Those nuclei fragmented almost immediately. Marathon claims to have produced stable gold-197 instead, through a different process that converts mercury-198 into mercury-197 before radioactive decay creates gold. The commercial stakes are larger than the laboratory record. On its website, Marathon models annual revenue of $223 million from electricity alone at a gigawatt-scale fusion plant, rising to $482 million when gold production is included. The implied $259 million increase depends on assumptions about output, prices, and the feasibility of operating a commercial reactor. Its July 2025 research projected roughly two metric tonnes of gold annually per gigawatt of thermal fusion power. The missing data from October's demonstration include a measured gold mass, isotope purity, recovery efficiency, and cost per gram. Without those figures, the reported experiment cannot establish whether artificial gold is a viable source of revenue, much less whether it could affect conventional gold supply. Marathon's nearer-term business is aimed at medical isotopes. It says its neutron experiments have already produced radioactive copper from zinc, while research published in December 2025 modeled ways to manufacture molybdenum-99 using small fusion systems operating below energy breakeven. The company's February 2026 paper estimated value per fusion neutron at around $10^-20 for gold or electricity and approximately $10^-10 for actinium-225, an isotope being developed for targeted cancer treatments. Those are modeled valuations, not realized sales or margins. Marathon joined the Canadian Nuclear Isotope Council in July, connecting it with an established medical-isotope industry. For now, the company's most relevant proof point is not whether gold can be created. It is whether its reported transmutation results can be converted into measurable, recoverable output at a cost customers can justify. Information for this briefing was found via the sources and the companies mentioned. The author has no securities or affiliations related to this organization. Not a recommendation to buy or sell. Always do additional research and consult a professional before purchasing a security. The author holds no licenses.

BetaKit
Sep 29th, 2026
Ex-General Fusion employee raises $4 million USD for fusion diagnostics startup Daedal.

Ex-General Fusion employee raises $4 million USD for fusion diagnostics startup Daedal. Toronto-based firm provides plasma measurement systems for fusion companies. A former employee of General Fusion has started his own company to make a standardized component to support companies working to generate fusion power. The news: Toronto-based Daedal Systems has raised just over $4 million USD ($5.7 million CAD) to develop standardized plasma measurement systems for the nuclear fusion industry. The round was led by OMERS Ventures, with participation from Garage Capital, Panache Ventures, Ripple Ventures, MaRS Investment Accelerator Fund, and a group of angel investors. Fusion developers need detailed plasma measurements to understand how their reactor designs perform. That component is often designed in-house by the developers. By specializing in this one component, Daedal wants to free up resources for those companies to focus on developing their reactors. The fledgling company will use its fresh funding to build its first three reactor diagnostic systems and deploy the prototypes with pilot customers. From the source: "After building and deploying plasma measurement systems at General Fusion, I saw the same challenge across the sector: every company needs high-quality diagnostics, but too much time and capital go into recreating similar systems in-house," Daedal founder and CEO Henry Gould said in a statement. "Daedal was created to solve that problem...and help them move faster toward commercialization." The context: The global race for commercial fusion power - an as-of-now theoretical method of harnessing energy from reactions similar to those that power the sun - has captured players from around the globe, from national labs to private companies like General Fusion, where Gould worked in many different roles from 2018 to 2025. The technology, if proven commercially viable, promises abundant, fossil-fuel-free power. Daedal did not disclose who its pilot customers are, however, a spokesperson told BetaKit that the firm has signed memoranda of understanding with fusion companies like Toronto-based Stellarex Energy, Proxima Fusion, OpenStar Technologies, and Marathon Fusion. Final thought: Daedal, which has a research partnership with the University of Wisconsin-Madison, claims its platform can adapt to different fusion machines and reactor approaches. While the company's initial focus is on the fusion industry, it said it has a longer-term ambition to become a major provider for other industries that require advanced measurement systems. Feature image courtesy Daedal Systems.

PR Newswire
Aug 27th, 2026
Marathon Fusion demonstrates lithium and hydrogen isotope enrichment with plasma centrifuge

Marathon Fusion has successfully enriched hydrogen and lithium isotopes using its proprietary plasma centrifuge technology. The San Francisco-based company is developing isotope production capabilities for the radiopharma and fusion industries. The plasma centrifuge enables differential pumping, which could reduce tritium flow rates and processing system sizes by a factor of ten or more. According to MIT Professor Dennis Whyte, the technology can improve fusion power plant performance whilst dramatically reducing required tritium inventory. Marathon's work addresses lithium enrichment, identified by the Special Competitive Studies Project as the highest risk supply chain gap in fusion energy, with no domestic commercial supply currently available. The company's development is supported by the US Department of Energy through the ARPA-E VISION OPEN programme. Marathon plans to progress towards demonstrating its first commercial pilot facility capable of producing isotopes to enable gigawatt-scale fusion deployments.

Medium
Aug 9th, 2025
Marathon Fusion: $9.9M for Nuclear Gold Breakthrough

Marathon Fusion, a San Francisco startup, has developed a method to produce gold from mercury isotopes using nuclear fusion reactors. The company raised $6 million in private funding and $4 million in government grants. Their process could generate 5,000 kg of gold annually, potentially doubling fusion plant revenue by combining energy and gold production. Scientific validation is pending, with a research paper awaiting peer review.

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