Mark Wayne Peres - 19 Feb 2026 Form 4 Insider Report for DEEP FISSION, INC.

Role: Chief Nuclear Officer
Signature: /s/ Jon Gordon as attorney-in-Fact for Mark Peres
Issuer symbol: N/A
Transactions as of: 19 Feb 2026
Net transactions value: $0
Form type: 4
Filing time: 23 Feb 2026, 21:10:58 UTC
Next filing: 10 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Peres Mark Wayne	Chief Nuclear Officer	C/O DEEP FISSION, INC., 2001 ADDISON STREET, SUITE 300, BERKELEY	/s/ Jon Gordon as attorney-in-Fact for Mark Peres	23 Feb 2026	0002110467

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction		Restricted Stock Unit	Award	$0	+25,000		$0.000000	25,000	19 Feb 2026	Common Stock	25,000	$0.000000	Direct	F1
transaction		Employee Stock Option (right to buy)	Award	$0	+15,000		$0.000000	15,000	19 Feb 2026	Common Stock	15,000	$15.00	Direct	F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each RSU vests based on attainment of both a service-based vesting condition and liquidity event vesting condition, in each case, prior to the expiration date. 25% of the service-based vesting condition will be satisfied on the one-year anniversary of the grant date and the remainder in equal monthly installments thereafter, subject to the reporting person's continued service through the vesting dates. The liquidity event condition will be satisfied on the earliest to occur of a change in control, initial public offering or direct listing.
F2	Date at which first vesting occurs is indicated. One-fourth of the total number of options to purchase the Company's common stock vests on the first vesting date shown and an additional one-thirty sixth on each month thereafter until fully vested.

Content

Each RSU vests based on attainment of both a service-based vesting condition and liquidity event vesting condition, in each case, prior to the expiration date. 25% of the service-based vesting condition will be satisfied on the one-year anniversary of the grant date and the remainder in equal monthly installments thereafter, subject to the reporting person's continued service through the vesting dates. The liquidity event condition will be satisfied on the earliest to occur of a change in control, initial public offering or direct listing.

Date at which first vesting occurs is indicated. One-fourth of the total number of options to purchase the Company's common stock vests on the first vesting date shown and an additional one-thirty sixth on each month thereafter until fully vested.