Form: D

Notice of Exempt Offering of Securities

September 23, 2025

The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

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

Notice of Exempt Offering of Securities
OMB APPROVAL
OMB Number: 3235-0076
Estimated average burden
hours per response: 4.00

1. Issuer's Identity

CIK (Filer ID Number) Previous Names
   None
Entity Type
0001918102
Surfside Acquisition Inc.
X Corporation
   Limited Partnership
   Limited Liability Company
   General Partnership
   Business Trust
   Other (Specify)

Name of Issuer
DEEP FISSION, INC.
Jurisdiction of Incorporation/Organization
DELAWARE
Year of Incorporation/Organization
   Over Five Years Ago
X Within Last Five Years (Specify Year) 2021
   Yet to Be Formed

2. Principal Place of Business and Contact Information

Name of Issuer
DEEP FISSION, INC.
Street Address 1 Street Address 2
2831 Garber Street
City State/Province/Country ZIP/PostalCode Phone Number of Issuer
Berkeley CALIFORNIA 94705 (707) 400-0778

3. Related Persons

Last Name First Name Middle Name
Muller Elizabeth A.
Street Address 1 Street Address 2
c/o Deep Fission, Inc. 2831 Garber Street
City State/Province/Country ZIP/PostalCode
Berkeley CALIFORNIA 94705
Relationship: X Executive Officer X Director    Promoter

Clarification of Response (if Necessary):

Last Name First Name Middle Name
Muller Richard A.
Street Address 1 Street Address 2
c/o Deep Fission, Inc. 2831 Garber Street
City State/Province/Country ZIP/PostalCode
Berkeley CALIFORNIA 94705
Relationship: X Executive Officer X Director    Promoter

Clarification of Response (if Necessary):

Last Name First Name Middle Name
Schmitz William Mark
Street Address 1 Street Address 2
c/o Deep Fission, Inc. 2831 Garber Street
City State/Province/Country ZIP/PostalCode
Berkeley CALIFORNIA 94705
Relationship: X Executive Officer    Director    Promoter

Clarification of Response (if Necessary):

4. Industry Group

   Agriculture
Banking & Financial Services
   Commercial Banking
   Insurance
   Investing
   Investment Banking
   Pooled Investment Fund
Is the issuer registered as
an investment company under
the Investment Company
Act of 1940?
   Yes    No
   Other Banking & Financial Services
   Business Services
Energy
   Coal Mining
   Electric Utilities
   Energy Conservation
   Environmental Services
   Oil & Gas
X Other Energy
Health Care
   Biotechnology
   Health Insurance
   Hospitals & Physicians
   Pharmaceuticals
   Other Health Care
   Manufacturing
Real Estate
   Commercial
   Construction
   REITS & Finance
   Residential
   Other Real Estate
  
 Retailing
  
 Restaurants
Technology
   Computers
   Telecommunications
   Other Technology
Travel
   Airlines & Airports
   Lodging & Conventions
   Tourism & Travel Services
   Other Travel
  
 Other

5. Issuer Size

Revenue Range OR Aggregate Net Asset Value Range
   No Revenues    No Aggregate Net Asset Value
   $1 - $1,000,000    $1 - $5,000,000
   $1,000,001 - $5,000,000    $5,000,001 - $25,000,000
   $5,000,001 - $25,000,000    $25,000,001 - $50,000,000
   $25,000,001 - $100,000,000    $50,000,001 - $100,000,000
   Over $100,000,000    Over $100,000,000
X Decline to Disclose    Decline to Disclose
   Not Applicable    Not Applicable

6. Federal Exemption(s) and Exclusion(s) Claimed (select all that apply)

Rule 504, 505, 506 and Section 4(a)(5) Exemptions Rule 506(b) and 506(c) Exemptions
   Rule 504(b)(1) (not (i), (ii) or (iii))
   Rule 504 (b)(1)(i)
   Rule 504 (b)(1)(ii)
   Rule 504 (b)(1)(iii)
X Rule 506(b)
   Rule 506(c)
   Securities Act Section 4(a)(5)
   Investment Company Act Section 3(c)
   Section 3(c)(1)    Section 3(c)(9)  
   Section 3(c)(2)    Section 3(c)(10)
   Section 3(c)(3)    Section 3(c)(11)
   Section 3(c)(4)    Section 3(c)(12)
   Section 3(c)(5)    Section 3(c)(13)
   Section 3(c)(6)    Section 3(c)(14)
   Section 3(c)(7)

7. Type of Filing

X New Notice Date of First Sale 2025-09-05    First Sale Yet to Occur
   Amendment

8. Duration of Offering

Does the Issuer intend this offering to last more than one year?
   Yes X No

9. Type(s) of Securities Offered (select all that apply)

Type of Security Type of Security
X Equity    Pooled Investment Fund Interests
   Debt    Tenant-in-Common Securities
X Option, Warrant or Other Right to Acquire Another Security    Mineral Property Securities
X Security to be Acquired Upon Exercise of Option, Warrant or Other Right to Acquire Security    Other (describe)

10. Business Combination Transaction

Is this offering being made in connection with a business combination transaction, such as a merger, acquisition or exchange offer?
X Yes    No

Clarification of Response (if Necessary):

Securities were sold to accredited investors immediately following closing of a reverse merger between Deep Fission Nuclear Inc. (fka Deep Fission Inc., "DFNI") and Deep Fission Acquisition Co., with DFNI surviving the merger as our wholly-owned sub.

11. Minimum Investment

Minimum investment accepted from any outside investor $0 USD

12. Sales Compensation

Recipient
Recipient CRD Number    None
Seaport Global Securities LLC 000116270
(Associated) Broker or Dealer X None
(Associated) Broker or Dealer CRD Number X None
None None
Street Address 1 Street Address 2
360 Madison Ave 22nd Floor
City State/Province/Country ZIP/Postal Code
New York NEW YORK 10017
State(s) of Solicitation (select all that apply)
Check “All States” or check individual States		    All States
X Foreign/non-US
CALIFORNIA
COLORADO
FLORIDA
GEORGIA
MARYLAND
MASSACHUSETTS
MINNESOTA
MISSOURI
NEW JERSEY
NEW YORK
PENNSYLVANIA
TEXAS
WISCONSIN
Recipient
Recipient CRD Number    None
Phoenix Financial Services 000144403
(Associated) Broker or Dealer X None
(Associated) Broker or Dealer CRD Number X None
None None
Street Address 1 Street Address 2
100 Wall Street Floor 10
City State/Province/Country ZIP/Postal Code
New York NEW YORK 10005
State(s) of Solicitation (select all that apply)
Check “All States” or check individual States		    All States
   Foreign/non-US
CALIFORNIA
COLORADO
CONNECTICUT
FLORIDA
GEORGIA
IOWA
MICHIGAN
MISSISSIPPI
NEW JERSEY
NEW YORK
PENNSYLVANIA
VERMONT
Recipient
Recipient CRD Number    None
Network 1 Financial Securities, Inc. 000013577
(Associated) Broker or Dealer X None
(Associated) Broker or Dealer CRD Number X None
None None
Street Address 1 Street Address 2
The Galleria, Suite 241 2 Bridge Avenue
City State/Province/Country ZIP/Postal Code
Red Bank NEW JERSEY 07701
State(s) of Solicitation (select all that apply)
Check “All States” or check individual States		    All States
   Foreign/non-US
CALIFORNIA
FLORIDA
LOUISIANA
MARYLAND
OKLAHOMA
Recipient
Recipient CRD Number    None
The Benchmark Company, LLC 000022982
(Associated) Broker or Dealer X None
(Associated) Broker or Dealer CRD Number X None
None None
Street Address 1 Street Address 2
150 E 58th Street 17th Floor
City State/Province/Country ZIP/Postal Code
New York NEW YORK 10155
State(s) of Solicitation (select all that apply)
Check “All States” or check individual States		    All States
X Foreign/non-US
CALIFORNIA
FLORIDA
WASHINGTON
Recipient
Recipient CRD Number    None
Dinosaur Financial Group, L.L.C. 000104446
(Associated) Broker or Dealer X None
(Associated) Broker or Dealer CRD Number X None
None None
Street Address 1 Street Address 2
33 Whitehall St. Ste. 1102
City State/Province/Country ZIP/Postal Code
New York NEW YORK 10004
State(s) of Solicitation (select all that apply)
Check “All States” or check individual States		    All States
X Foreign/non-US
CALIFORNIA
FLORIDA
NEW JERSEY
NEW YORK

13. Offering and Sales Amounts

Label Amount Currency Indefinite
Total Offering Amount $31,759,998 USD
or    Indefinite
Total Amount Sold $30,000,000 USD
Total Remaining to be Sold $1,759,998 USD
or    Indefinite

Clarification of Response (if Necessary):

Includes amounts receivable upon exercise of warrants to purchase 586,666 shares of common stock with the exercise price of $3.00 per share issued to the placement agents; such warrants have not yet been exercised.

14. Investors

  
 Select if securities in the offering have been or may be sold to persons who do not qualify as accredited investors, and enter the number of such non-accredited investors who already have invested in the offering.
Regardless of whether securities in the offering have been or may be sold to persons who do not qualify as accredited investors, enter the total number of investors who already have invested in the offering:
100

15. Sales Commissions & Finder's Fees Expenses

Provide separately the amounts of sales commissions and finders fees expenses, if any. If the amount of an expenditure is not known, provide an estimate and check the box next to the amount.

Sales Commissions $2,100,000 USD
   Estimate
Finders' Fees $0 USD
   Estimate

Clarification of Response (if Necessary):

16. Use of Proceeds

Provide the amount of the gross proceeds of the offering that has been or is proposed to be used for payments to any of the persons required to be named as executive officers, directors or promoters in response to Item 3 above. If the amount is unknown, provide an estimate and check the box next to the amount.

$0 USD
   Estimate

Clarification of Response (if Necessary):

Signature and Submission

Please verify the information you have entered and review the Terms of Submission below before signing and clicking SUBMIT below to file this notice.

Terms of Submission

In submitting this notice, each issuer named above is:
  • Notifying the SEC and/or each State in which this notice is filed of the offering of securities described and undertaking to furnish them, upon written request, in the accordance with applicable law, the information furnished to offerees.*
  • Irrevocably appointing each of the Secretary of the SEC and, the Securities Administrator or other legally designated officer of the State in which the issuer maintains its principal place of business and any State in which this notice is filed, as its agents for service of process, and agreeing that these persons may accept service on its behalf, of any notice, process or pleading, and further agreeing that such service may be made by registered or certified mail, in any Federal or state action, administrative proceeding, or arbitration brought against the issuer in any place subject to the jurisdiction of the United States, if the action, proceeding or arbitration (a) arises out of any activity in connection with the offering of securities that is the subject of this notice, and (b) is founded, directly or indirectly, upon the provisions of:  (i) the Securities Act of 1933, the Securities Exchange Act of 1934, the Trust Indenture Act of 1939, the Investment Company Act of 1940, or the Investment Advisers Act of 1940, or any rule or regulation under any of these statutes, or (ii) the laws of the State in which the issuer maintains its principal place of business or any State in which this notice is filed.
  • Certifying that, if the issuer is claiming a Regulation D exemption for the offering, the issuer is not disqualified from relying on Rule 504 or Rule 506 for one of the reasons stated in Rule 504(b)(3) or Rule 506(d).

Each Issuer identified above has read this notice, knows the contents to be true, and has duly caused this notice to be signed on its behalf by the undersigned duly authorized person.

For signature, type in the signer's name or other letters or characters adopted or authorized as the signer's signature.

Issuer Signature Name of Signer Title Date
DEEP FISSION, INC. /s/ Elizabeth A. Muller Elizabeth A. Muller President and CEO 2025-09-22

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.

* This undertaking does not affect any limits Section 102(a) of the National Securities Markets Improvement Act of 1996 ("NSMIA") [Pub. L. No. 104-290, 110 Stat. 3416 (Oct. 11, 1996)] imposes on the ability of States to require information. As a result, if the securities that are the subject of this Form D are "covered securities" for purposes of NSMIA, whether in all instances or due to the nature of the offering that is the subject of this Form D, States cannot routinely require offering materials under this undertaking or otherwise and can require offering materials only to the extent NSMIA permits them to do so under NSMIA's preservation of their anti-fraud authority.