Deep Fission, Inc. (Ticker: FISN US) is an American development-stage nuclear energy technology company developing a small modular reactor based on established pressurized water reactor technology for emplacement in deep boreholes about one mile below the surface. Deep Fission plans to list on NASDAQ on May 29, 2026, offering 6.0 million shares at $24.00 to $26.00 per share, raising approximately $150 million at the midpoint. The company is incorporated in Delaware and has not generated revenue.

Deep Fission’s Gravity Reactor is intended to use subsurface pressure, geology and shielding to reduce reliance on large surface containment structures. The company is advancing engineering validation, drilling research, safety analysis, regulatory engagement and site development, including work at its leased site in Parsons, Kansas. Estimated market capitalization is approximately $1.6 billion.