Key Takeaways
- • Antares secures $470M Series C funding ($370M equity + $100M debt) co-led by Paradigm and Caffeinated Capital to accelerate deployment of military-focused nuclear microreactors, with target deployment on military installations by 2028.
- • Antares achieved criticality with Mark-0 reactor in June 2026—becoming the first privately developed non-light-water reactor to reach criticality in the U.S. in over 40 years, and the first among DOE's Reactor Pilot Program cohort to hit the milestone.
- • Capital efficiency advantage: Antares achieved criticality with approximately $134M in total raised capital—the lowest amount among four companies that met the DOE's July 4, 2026 criticality deadline (ahead of Valar Atomics, Deployable Energy, and Aalo Atomics).
- • Investor syndicate includes strategic players: Round participants include Point72 Ventures, Series B lead Shine Capital, and Industrious Ventures, alongside new co-lead Paradigm, signaling institutional confidence in military nuclear power applications.
- • Nuclear SMR sector experiencing significant growth momentum as Department of Defense seeks resilient energy solutions; Antares positions itself as the leading contender in the DOE's Reactor Pilot Program for fielding small modular reactors in defense applications.
Summary
Antares, a Los Angeles-based space and defense-focused nuclear startup, closed a $470 million Series C funding round designed to accelerate the development and deployment of military-grade nuclear microreactors. The round comprised $370 million in equity and $100 million in debt financing, co-led by Paradigm and Caffeinated Capital, with participation from Point72 Ventures, Shine Capital, Industrious Ventures, and other institutional investors. CEO Jordan Bramble stated the capital will fund reactor construction and operational deployment on military installations by 2028.
The funding announcement comes on the heels of a significant technical milestone. In June 2026, Antares' Mark-0 test reactor achieved criticality—the point at which a nuclear fission chain reaction becomes self-sustaining. This achievement marked "the first time in more than four decades that a new privately developed non-light-water reactor has reached criticality in the United States," according to Energy Secretary Chris Wright. Antares crossed this milestone ahead of its three competitors in the Department of Energy's Reactor Pilot Program, completing the feat with the least capital deployment among the cohort.
The DOE's Reactor Pilot Program, launched in June 2025, set an ambitious goal for three of ten participating startups to achieve criticality by July 4, 2026. Four companies ultimately met or exceeded this deadline: Antares (June 2026), followed by Valar Atomics, Deployable Energy, and Aalo Atomics. Antares accomplished its criticality milestone while having raised only approximately $134 million in total funding, including a $96 million Series B in December 2025—a capital efficiency that distinguishes it within the nascent commercial SMR sector.
The funding reflects accelerating investor interest in small modular reactors designed to address the Pentagon's growing demand for resilient, distributed energy infrastructure. As the nuclear energy startup landscape experiences what industry observers characterize as a "gold rush," Antares has positioned itself as the leading private developer capable of meeting near-term defense sector requirements. The 2028 deployment target and substantial capital raise underscore the startup's trajectory toward operationalizing military nuclear power systems at scale.
The funding announcement comes on the heels of a significant technical milestone. In June 2026, Antares' Mark-0 test reactor achieved criticality—the point at which a nuclear fission chain reaction becomes self-sustaining. This achievement marked "the first time in more than four decades that a new privately developed non-light-water reactor has reached criticality in the United States," according to Energy Secretary Chris Wright. Antares crossed this milestone ahead of its three competitors in the Department of Energy's Reactor Pilot Program, completing the feat with the least capital deployment among the cohort.
The DOE's Reactor Pilot Program, launched in June 2025, set an ambitious goal for three of ten participating startups to achieve criticality by July 4, 2026. Four companies ultimately met or exceeded this deadline: Antares (June 2026), followed by Valar Atomics, Deployable Energy, and Aalo Atomics. Antares accomplished its criticality milestone while having raised only approximately $134 million in total funding, including a $96 million Series B in December 2025—a capital efficiency that distinguishes it within the nascent commercial SMR sector.
The funding reflects accelerating investor interest in small modular reactors designed to address the Pentagon's growing demand for resilient, distributed energy infrastructure. As the nuclear energy startup landscape experiences what industry observers characterize as a "gold rush," Antares has positioned itself as the leading private developer capable of meeting near-term defense sector requirements. The 2028 deployment target and substantial capital raise underscore the startup's trajectory toward operationalizing military nuclear power systems at scale.
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