Deep Fission, Inc. Common Stock

Deep Fission, Inc. is an American nuclear-energy company based in Berkeley, California. Founded in 2023 by Elizabeth Muller and her father, physicist Richard A. Muller, the company is developing an underground reactor concept it calls the Gravity Reactor, which it describes as a pressurized water reactor intended for emplacement in a deep borehole approximately one mile (1.6 km) below the surface. In August 2025, the U.S. Department of Energy (DOE) selected Deep Fission for its Reactor Pilot Program, a pathway for testing advanced reactors outside the national laboratories. It is a development-stage company and had not built or licensed a reactor as of 2026. Deep Fission became an SEC-reporting company through a reverse merger in 2025 and completed an initial public offering in June 2026; its shares trade on the Nasdaq under the ticker symbol FISN.