Mark Wayne Peres - 19 Feb 2026 Form 3 Insider Report for DEEP FISSION, INC.

Reporting relationship: Chief Nuclear Officer
Issuer ticker: FISN on Nasdaq
Reported as of: 19 Feb 2026
Net transaction value: $0
SEC form: 3
Accepted by SEC: 23 Feb 2026, 21:09:05 UTC
Next SEC filing: 10 Mar 2026
Source filing: View source filing
Reporting owner signature: /s/ Jon Gordon as attorney-in-Fact for Mark Peres

Key filing fact

Mark Wayne Peres filed Form 3 for DEEP FISSION, INC. on 23 Feb 2026.

Key facts

This page summarizes Mark Wayne Peres's Form 3 filing for DEEP FISSION, INC..
0 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 23 Feb 2026, 21:09.

Change

No earlier filing in this sequence is available for direct comparison.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Official SEC source

Ownership activity is grounded in SEC Form 3 disclosures.

View source filing

Reporting Owners (1)

CIK 0002110467 Primary reporting owner

Peres Mark Wayne

Relationship: Chief Nuclear Officer
Address: C/O DEEP FISSION, INC., 2001 ADDISON STREET, SUITE 300, BERKELEY
Signature: /s/ Jon Gordon as attorney-in-Fact for Mark Peres
Signature date: 23 Feb 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

No ticker holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 86,607
Date: 19 Feb 2026
Ownership: Direct
Footnotes: F1

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 1 footnote

Footnote F1

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.

SEC remarks

Exhibit 24: Power of Attorney attached herewith.