# EDGAR Filing Document

**Accession Number:** 0001918102
**File Stem:** 0001104659-26-018747
**Filing Date:** 2026-2
**Character Count:** 5974
**Document Hash:** ce31bd7059b9cb4a4f1a59aa7b1629ac
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-018747.hdr.sgml**: 20260223

**ACCESSION NUMBER**: 0001104659-26-018747

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 3

**CONFORMED PERIOD OF REPORT**: 20260219

**FILED AS OF DATE**: 20260223

**DATE AS OF CHANGE**: 20260223

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Peres Mark Wayne
- **CENTRAL INDEX KEY:** 0002110467

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-56407
- **FILM NUMBER:** 26667253

**MAIL ADDRESS:**
- **STREET 1:** 72 CASTELLAN DRIVE
- **CITY:** GREER
- **STATE:** SC
- **ZIP:** 29650
**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**

![](tm266857d1_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 any required Form ID, Forms 3, 4, and 5 (and any amendments) under Section 16(a) of the Securities Exchange Act of 1934, and any related documents with the U.S. Securities and Exchange Commission.

The undersigned grants each attorney-in-fact full power to act individually, in the name and on behalf of the undersigned, with the same effect as if the undersigned were personally present, and ratifies every lawful act done under this authorization. This Power of Attorney does not relieve the undersigned from responsibility for the timely and accurate filing of Forms 3, 4, and 5 or from any liability for failure to do so.

This Power of Attorney remains in effect until the undersigned provides written revocation to the Company'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 is governed by Delaware law.

---

| | |
|:---|:---|
| Signed: | /s/ Mark Peres |
| Name: | Mark Peres |
| Date: | February 23, 2026 |

---

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

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Peres Mark Wayne<br><sub>(Last) (First) (Middle)</sub><br>C/O DEEP FISSION, INC.<br>2001 ADDISON STREET, SUITE 300<br><sub>(Street)</sub><br>BERKELEY, CA 94704<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>DEEP FISSION, INC. [ NONE ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-02-19 | **4. 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 Nuclear Officer_ | **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 Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |
| Common Stock | 86607<sup>(1)</sup> | D |  |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) Reflects shares of common stock received in connection with the merger completed in September 2025. A portion of the shares are subject to the Company's right of repurchase at cost upon termination of service, which right lapses as the shares vest.

**Remarks:**
Exhibit 24: Power of Attorney attached herewith.

**Signature:** /s/ Jon Gordon as attorney-in-Fact for Mark Peres  
**Date:** 2026-02-23

### 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.**