Antares raises $470 million Series C for military nuclear microreactors

Antares has raised $470 million in Series C financing to commercialize advanced nuclear microreactors for defense and related uses, Startup Fortune and VentureBurn reported, citing a Dow Jones account of the round. According to Startup Fortune, Dow Jones said the financing was co-led by Paradigm and Caffeinated Capital and included $370 million in equity and $100 million in debt, with Point72 Ventures, Shine Capital, Industrious Ventures and others participating. Total funding is now past $600 million. VentureBurn reported the company will use the capital to deliver a first electricity-producing reactor in 2027 and begin military deployments in 2028. Startup Fortune said Antares Nuclear's Mark-0 reactor went critical at Idaho National Laboratory in a June 4 zero-power fueled demonstration under the Department of Energy's Reactor Pilot Program, sustaining a controlled chain reaction without producing electricity. The company, founded in 2023, raised $96 million in a Series B in December 2025. The outlet reported that the Department of the Air Force and the Defense Innovation Unit selected Joint Base San Antonio in April 2026 as a potential site under the Advanced Nuclear Power for Installations initiative and paired it with Antares, with siting and environmental review still ahead. Antares says its R1 microreactor is designed for 100 kilowatts to 1 megawatt of electricity for more than six years, using sodium heat pipes, TRISO fuel and a nitrogen Brayton cycle. VentureBurn said Antares was the first private company in over 40 years to achieve criticality with a non-light-water reactor in the United States.