Deep Fission Challenges Short-Seller Report, Vows Legal Review — Deep Fission, Inc.

Event summary

Deep Fission, Inc. (Nasdaq: FISN) rejected a short-seller report published on September 25, 2026, calling it misleading and containing inaccuracies.
The anonymous report disclosed a short position in Deep Fission securities, aiming to profit from a potential stock price decline.
Deep Fission CEO Elizabeth Muller stated the company is exploring legal remedies to correct the record.
The company is advancing its Gravity™ Nuclear Reactor project in Parsons, Kansas, and is part of the U.S. DOE’s Reactor Pilot Program.

The big picture

Deep Fission’s rebuttal of the short-seller report underscores the growing scrutiny facing nuclear energy startups as they navigate regulatory hurdles and market skepticism. The company’s underground reactor technology aims to address safety and scalability challenges, but its ability to withstand such attacks will be critical as it seeks commercial deployment. The U.S. DOE’s Reactor Pilot Program selection highlights the strategic importance of its work, but investor confidence remains a key variable.

What we're watching

Legal Response: Whether Deep Fission’s potential legal action will succeed in countering the short-seller’s claims and stabilizing investor confidence.
Regulatory Scrutiny: How the SEC and other regulators may respond to the short-seller report and Deep Fission’s countermeasures.
Technology Validation: The pace at which Deep Fission can demonstrate the safety and scalability of its Gravity™ Nuclear Reactor to regain market trust.