# EDGAR Filing Document

**Accession Number:** 0002081850
**File Stem:** 0001104659-25-120704
**Filing Date:** 2025-12
**Character Count:** 8329
**Document Hash:** 14eb96b4d8e929560b41c37843a57d80
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-120704.hdr.sgml**: 20251212

**ACCESSION NUMBER**: 0001104659-25-120704

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 3

**CONFORMED PERIOD OF REPORT**: 20251209

**FILED AS OF DATE**: 20251212

**DATE AS OF CHANGE**: 20251212

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Muller Elizabeth
- **CENTRAL INDEX KEY:** 0002081850

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-56407
- **FILM NUMBER:** 251569004

**MAIL ADDRESS:**
- **STREET 1:** 2001 ADDISON STREET
- **STREET 2:** SUITE 300
- **CITY:** BERKELEY
- **STATE:** CA
- **ZIP:** 94704
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** DEEP FISSION, INC.
- **CENTRAL INDEX KEY:** 0001918102
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC SERVICES [4911]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 874265302
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 2831 GARBER STREET
- **CITY:** BERKELEY
- **STATE:** CA
- **ZIP:** 94705
- **BUSINESS PHONE:** (707) 400-0778

**MAIL ADDRESS:**
- **STREET 1:** 2831 GARBER STREET
- **CITY:** BERKELEY
- **STATE:** CA
- **ZIP:** 94705

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Surfside Acquisition Inc.
- **DATE OF NAME CHANGE:** 20220317

## Ex-24

**Exhibit 24**

![](tm2531523d5_ex24img001.jpg)

**Power of Attorney for SEC Forms 3, 4 and 5**

The undersigned appoints and authorizes each of Mark Schmitz, Chief Financial Officer, and Jon Gordon, General Counsel & Secretary of Deep Fission Inc., as attorneys-in-fact with authority to prepare, sign, and file on behalf of the undersigned any and all Forms 3, 4, and 5 (including any amendments thereto) required to be filed under Section 16(a) of the Securities Exchange Act of 1934, and any related documents necessary or appropriate in connection with such filings.

The undersigned grants each attorney-in-fact full power and authority to act individually, in the name and on behalf of the undersigned, with the same force and effect as if the undersigned were personally present, and hereby ratifies and confirms all lawful actions taken pursuant to this Power of Attorney. This Power of Attorney does not relieve the undersigned of responsibility for timely and accurate compliance with Section 16 or from any liability arising from failure to do so.

This Power of Attorney remains in effect until the undersigned provides written revocation to Deep Fission's General Counsel or until the undersigned ceases to be subject to Section 16 with respect to the Company's securities, whichever occurs first. This Power of Attorney shall be governed by the laws of the State of Delaware.

---

| | |
|:---|:---|
| Signed: | /s/ Elizabeth Muller |
| Name: | Elizabeth Muller |
| Date: | December 11, 2025 |

---

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] 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**<sup>*</sup><br>Muller Elizabeth<br><sub>(Last) (First) (Middle)</sub><br>2831 GARBER STREET<br><sub>(Street)</sub><br>BERKELEY, CA 94705<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-12-09 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_Chief Executive Officer_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>DEEP FISSION, INC. [ NONE ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Restricted Stock Units | 2025-12-09 |  | A<sup>(1)</sup> |  | 549451 | A | $0 | 549451 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Stock Option (right to buy) | $2.73 | 2025-12-09 |  | A |  | 183150 |  | <sup>(2)</sup> | 2035-12-09 | shares of Common Stock | 183150 | $0 | 994849 | D |  |

---

### Footnotes:

(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.

**Signature:** /s/ Jon Gordon, as Attorney-in-Fact for Elizabeth Muller  
**Date:** 2025-12-12

### Remarks:

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.**