4: Statement of changes in beneficial ownership of securities
Published on December 12, 2025
| FORM 4 |
UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIPFiled pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940 |
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| Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). | ||||||||||||||||
| Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10. | ||||||||||||||||
1. Name and Address of Reporting Person*
(Street)
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2. Issuer Name and Ticker or Trading Symbol
DEEP FISSION, INC. [ NONE ] |
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
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3. Date of Earliest Transaction
(Month/Day/Year) 12/09/2025 | ||||||||||||||||||||||||||
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4. If Amendment, Date of Original Filed
(Month/Day/Year) |
6. Individual or Joint/Group Filing (Check Applicable Line)
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| 1. Title of Security (Instr. 3) | 2. Transaction Date (Month/Day/Year) | 2A. Deemed Execution Date, if any (Month/Day/Year) | 3. Transaction Code (Instr. 8) | 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) | 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) | 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) | 7. Nature of Indirect Beneficial Ownership (Instr. 4) | |||
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| Code | V | Amount | (A) or (D) | Price | ||||||
| Restricted Stock Units | 12/09/2025 | A(1) | 549,451 | A | $0 | 549,451 | D | |||
| 1. Title of Derivative Security (Instr. 3) | 2. Conversion or Exercise Price of Derivative Security | 3. Transaction Date (Month/Day/Year) | 3A. Deemed Execution Date, if any (Month/Day/Year) | 4. Transaction Code (Instr. 8) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) | 6. Date Exercisable and Expiration Date (Month/Day/Year) | 7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) | 8. Price of Derivative Security (Instr. 5) | 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) | 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) | 11. Nature of Indirect Beneficial Ownership (Instr. 4) | ||||
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| Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | ||||||||
| Stock Option (right to buy) | $2.73 | 12/09/2025 | A | 183,150 | (2) | 12/09/2035 | shares of Common Stock | 183,150 | $0 | 994,849 | D | ||||
| Explanation of Responses: |
| 1. Each restricted stock unit represents the contingent right to receive one share of the Issuer's common stock upon vesting. The units vest over four years, with 25% of the award vesting on the first anniversary of the December 9, 2025 grant date and the remaining 75% vesting in equal monthly installments thereafter, subject to the Reporting Person's continued service through each vesting date. Restricted stock units do not have an expiration date. |
| 2. The stock options vest over four years, with 25% of the award vesting on the first anniversary of the December 9, 2025 grant date and the remaining 75% vesting in equal monthly installments thereafter, subject to the Reporting Person's continued service through each vesting date. |
| Remarks: |
| Chief Executive Officer (Section 16 Officer). The equity awards reported herein were approved by the Issuer's Compensation Committee pursuant to Rule 16b-3. Power of Attorney authorizing the signer to execute and file this Form 4 on behalf of the Reporting Person is filed as Exhibit 24. |
| /s/ Jon Gordon, as Attorney-in-Fact for Elizabeth Muller | 12/12/2025 | |
| ** Signature of Reporting Person | Date |
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.