Deep Fission, Inc. priced its initial public offering at $16.00 a share, to list on the Nasdaq Global Market under the symbol FISN. It filed a Form S-1 registration statement for an initial public offering on September 22, 2025. As of November 6, 2026, its final prospectus is on file (Form 424B4, June 18, 2026).
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Key facts
Deep Fission, Inc. filed a Form S-1 registration statement for an initial public offering on 2025-09-22. It has amended it 6 times. It filed its final prospectus on 2026-06-18, at a public offering price of $16.00 per share. Each fact below is quoted from the filing named with it.
Also on the record for Deep Fission, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| May 15, 2026 | Stake report, Schedule 13G/A, by Mark N.Tompkins | 5.6% of the class | 5%+ stakes | Source |
| February 18, 2026 | Form D, private offering | $80M sold | Form D page | Source |
| November 14, 2025 | Stake report, Schedule 13G/A, by Mark N. Tompkins | 5.82% of the class | 5%+ stakes | Source |
| November 3, 2025 | Stake report, Schedule 13G, by EE HOLDINGS LIMITED | 5.5% of the class | 5%+ stakes | Source |
| September 24, 2025 | Form D, private offering | — | Form D page | Source |
| September 23, 2025 | Form D, private offering | $30M sold | Form D page | Source |
| September 23, 2025 | Stake report, Schedule 13D, by Muller Elizabeth | 20.6% of the class | 5%+ stakes | Source |
| September 23, 2025 | Stake report, Schedule 13D, by Muller Richard | 10.6% of the class | 5%+ stakes | Source |
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More on Deep Fission, Inc. and the records around it.
Deep Fission, Inc. elsewhere on the record
- 5%+ stake filings May 2026
- Company profile and every filing Feb 2026
- Form D filing Feb 2026
- Form D filing Sep 2025
- Who owns it
Companies that share a holder
- Muller Elizabeth also filed stake reports on 1 other company: DEEP ISOLATION NUCLEAR, INC. (Aug 2025)
- Muller Richard also filed stake reports on 1 other company: DEEP ISOLATION NUCLEAR, INC. (Aug 2025)
- Mark N. Tompkins also filed stake reports on 8 other companies: Los Altos Ventures Corp. (Jun 2026), Aeluma, Inc. (May 2026), Deep Isolation Nuclear, Inc. (May 2026)
Also filing to list on the Nasdaq Global Market
IPO filings on the Nasdaq Global Market in Q2 2026, newest first.
- AMASS BRANDS (Jun 2026)
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What the filings say
Listing
We have been approved to list our common stock on the Nasdaq Global Market (“Nasdaq”) under the symbol “FISN”.From the 424B4 filed 2026-06-18
Offering price
on an as further adjusted basis to give effect to (i) the adjustments set forth in the immediately preceding bullet and (ii) the issuance and sale by us of shares of common stock in this offering at a public offering price of $16.00 per share of common stock.From the 424B4 filed 2026-06-18
Use of proceeds
We intend to use the net proceeds to us from this offering for general working capital and corporate purposes, including towards the engineering, research and development, licensing and construction of our first pilot nuclear reactor and related technologies.From the 424B4 filed 2026-06-18
Net loss or income
During the three months ended March 31, 2026 and the years ended December 31, 2025 and 2024, we incurred net losses of $21.3 million, $61.0 million and $5.7 million, respectively.From the S-1/A filed 2026-06-10
Timeline
| Filed | What it is | Filing |
|---|---|---|
| 2025-09-22 | Registration statement filed | S-1 |
| 2025-09-24 | Registration statement amended | S-1/A |
| 2025-12-01 | Registration statement amended | S-1/A |
| 2025-12-30 | Registration statement amended | S-1/A |
| 2026-01-27 | Registration statement amended | S-1/A |
| 2026-02-17 | Registration statement filed | S-1 |
| 2026-04-21 | Registration statement amended | S-1/A |
| 2026-05-20 | Registration statement filed | S-1 |
| 2026-06-10 | Registration statement amended | S-1/A |
| 2026-06-18 | Final prospectus filed: the offering is priced | 424B4 |
Deep Fission, Inc.'s full funding historyFounders and team
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Where this comes from
A company that wants to sell shares to the public in the United States files a registration statement with the SEC: Form S-1 for a US company, Form F-1 for a foreign one. It amends that statement as the figures and terms are filled in, usually adding the expected price range shortly before the offering. Once the offering is priced it files its final prospectus under Rule 424(b)(4). A company that decides not to go ahead can ask for the registration statement to be withdrawn on Form RW.
Every row on this page is one of those filings, linked to the filing itself. The facts are the company's own sentences, quoted from the filing named beside each one and never reworded; where no filing states a fact in a sentence that can be read exactly, this page leaves it out. A filing is the company's statement of its plans and its figures, not a verification of them, and nothing here is investment advice.