Deep Fission, Inc. (FISN)

Deep Fission, Inc. is a nuclear energy company developing small modular reactors designed to be installed at the bottom of deep boreholes, roughly a mile underground. Placing the reactor deep in the earth is intended to use the surrounding rock and water column for natural shielding and pressure, reducing the need for large surface containment structures.

The company plans to offer its reactors in scalable configurations, either to supply power on site to customers or to sell electricity into wholesale power markets. Target customers include utilities, data centers, heavy industry, the military, government agencies and cities. Deep Fission also handles regulatory licensing and provides advisory and partnership services.

Deep Fission was founded in 2023 and is headquartered in Berkeley, California. Its common stock began trading on the Nasdaq Stock Market under the ticker FISN in 2026.