Deep Fission seeks $157 million IPO as nuclear startup faces skepticism

Deep Fission is asking Wall Street to price a nuclear startup built on a promise of underground reactors, even as its own filings warn that the company may run out of money within 12 months if the offering fails. The company’s May 20 S-1 seeks as much as $156 million to $157 million in a Nasdaq IPO at $24 to $26 a share, implying a valuation of about $1.66 billion for a business that is still drilling, still pre-revenue and still trying to prove its core concept.

The pitch is unusually specific. Deep Fission says it plans to build 15-megawatt pressurized-water reactors and lower them into 30-inch-diameter holes drilled one mile underground, arguing that depth can improve safety and security by reducing the risk of a meltdown or attack. The startup says it started drilling the first of three test wells in March 2026, but the timetable has already slipped. In December 2025, Deep Fission had said it hoped to reach criticality by July 2026; the new filing gives no date for that milestone.

Investors will also have to reconcile the new IPO with the company’s earlier public-market move. Deep Fission completed a reverse merger with Surfside Acquisition, a Delaware shell company, on September 5, 2025, and raised $30 million in a concurrent private placement at $3 a share. That listing never actually traded on OTCQB, despite the company’s prior plan to quote there, making the new Nasdaq route a reset rather than a continuation.

The financial picture is tighter now than it was a few months ago. Deep Fission’s deficit grew to $88.1 million in March 2026 from $56.2 million earlier, while cash and cash equivalents fell by $6.4 million, or about 7%, in roughly a month and a half. The S-1 repeats the same going-concern warning found in earlier financial statements, underscoring how dependent the company is on raising new capital.

Deep Fission’s backers are selling a story aligned with the broader nuclear startup boom driven by AI and data-center power demand. In January 2025, the company and Endeavour Energy announced a 2-gigawatt partnership to co-develop underground nuclear power for data centers, with first reactors expected in 2029 and power priced at 5 to 7 cents per kWh. Deep Fission also says it was selected for the Department of Energy’s Reactor Pilot Program and announced a fuel deal with Urenco USA in February 2026.

Founded in 2023 by Elizabeth Muller and Richard Muller, Deep Fission says it has 40-plus patent-protected inventions. The question for public investors is whether those filings, partnerships and patents amount to a credible path to commercialization, or only a costly bet on an unproven nuclear concept still several years from revenue.