Richard Muller - 05 Sep 2025 Form 4 Insider Report for DEEP FISSION, INC.

Reporting relationship: Chief Technology Officer, Director
Issuer ticker: FISN
Reported as of: 05 Sep 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 09 Sep 2025, 17:43:39 UTC
Next SEC filing: 10 Mar 2026
Source filing: View source filing
Reporting owner signature: /s/ Richard Muller

Key filing fact

Richard Muller filed Form 4 for DEEP FISSION, INC. on 09 Sep 2025.

Key facts

This page summarizes Richard Muller's Form 4 filing for DEEP FISSION, INC..
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 09 Sep 2025, 17:43.

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

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002081872 Primary reporting owner

Muller Richard

Relationship: Chief Technology Officer, Director
Address: C/O DEEP FISSION, INC., 2831 GARBER STREET, BERKELEY
Signature: /s/ Richard Muller
Signature date: 09 Sep 2025

Reported non-derivative transactions

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

No ticker transaction

Common Stock

Award

Transaction value
Shares: +5,196,426
Change %
Price
Shares after: 5,196,426
Date: 05 Sep 2025
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

Received in connection with the Issuer's merger (the "Merger") with Deep Fission Inc. ("Legacy Deep Fission") in accordance with the terms of the Agreement and Plan of Merger and Reorganization dated as of September 5, 2025, by and among the Issuer (f/k/a Surfside Acquisition Inc.), Deep Fission Acquisition Co. and Legacy Deep Fission (the "Merger Agreement"), in exchange for shares of Legacy Deep Fission common stock. Pursuant to the terms of the Merger Agreement, at the effective time of the Merger, each issued and outstanding share of Legacy Deep Fission common stock was converted into the right to receive 17.32142 shares of the Issuer's common stock, rounded to the nearest whole share.