Deep Fission prices $40 million public offering at $16 a share

Deep Fission, an advanced nuclear startup developing small modular reactors installed one mile underground, priced its public offering at $16 a share, raising $40 million to fund its unproven Gravity Reactor technology in southeast Kansas.

"Investing in our common stock involves a high degree of risk," the company said in its SEC filing. "Our Gravity Reactor is unproven, and our design, borehole development activities, planned pilot reactor, and future commercial applications may fail, progress more slowly than projected, or encounter delays or changes that increase costs and capital requirements."

The offering consists of 2.5 million shares, with underwriters holding a 30-day option to purchase an additional 375,000 shares. Deep Fission initially filed in May to offer about 6 million shares at $24 to $26 before revising both the share count and price range downward. The company has drilled its first data-gathering well at the Great Plains Industrial Park in Parsons, Kansas, and plans to demonstrate a commercial-scale borehole and deploy a prototype reactor in the coming months.

Deep Fission aims to apply for a commercial license with the Nuclear Regulatory Commission in early 2027. Its technology — a small modular pressurized water reactor, or SMR, designed to operate in boreholes a mile underground — has never been deployed commercially. The company partnered with the U.S. Department of Energy to build the pilot project. Shares will trade on Nasdaq under the ticker FISN.

The public offering comes as investor appetite for advanced nuclear startups remains strong, though the technology faces skepticism in communities where projects are proposed. In Parsons, some residents have raised concerns about hosting an untested reactor, with local activist Fran Tompkins saying the area does not want to be "lab rats." Deep Fission's $40 million raise is modest compared with peers such as NuScale Power, which has raised over $1 billion in public and private capital, and TerraPower, backed by Bill Gates with significant DOE funding.

The company's revised terms — cutting the share count by more than half and lowering the price range — suggest tepid demand from institutional investors. Deep Fission did not disclose the underwriters for the offering or the expected closing date.

This article is for informational purposes only and does not constitute investment advice.