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  4. [Form 4] DEEP FISSION, INC. Insider Trading Activity

Deep Fission, Inc. (FISN) director granted 19,156 restricted stock units

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

GLANVILLE THOMAS S reported acquisition or exercise transactions in this Form 4 filing.

DEEP FISSION, INC. director GLANVILLE THOMAS S received a grant of 19,156 restricted stock units on July 23, 2026. Each unit represents a contingent right to receive one share of common stock and will vest on July 20, 2027, provided he continues to provide service through that date. Following this award, his directly held RSU balance is 19,156 units.

Positive

  • None.

Negative

  • None.
Insider GLANVILLE THOMAS S
Role Director
Type Security Shares Price Value
Grant/Award Restricted Stock Unit F1 19,156 $0.00 $0.00
Holdings After Transaction: Restricted Stock Unit — 19,156 shares (Direct)
Footnotes (1)
  1. F1. Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock upon vesting. The units vest on July 20, 2027, provided the holder continues to provide service through the vesting date.
Restricted stock units granted 19156.0000 Grant of RSUs to director on 2026-07-23
Transaction price per RSU 0.0000 Equity award with no cash price per unit
RSUs outstanding after grant 19156.0000 Total directly held restricted stock units following the award
Vesting date July 20, 2027 Units vest if service continues through this date
Restricted Stock Unit financial
"Each restricted stock unit represents a contingent right to receive one share"
A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.
contingent right financial
"represents a contingent right to receive one share of the Issuer's common stock"
vest financial
"The units vest on July 20, 2027, provided the holder continues to provide service"
A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Form 4 Insider Transactions: What Each Field Means →

FAQ

What equity award did GLANVILLE THOMAS S report for DEEP FISSION, INC. (FISN)?
GLANVILLE THOMAS S reported a grant of 19,156 restricted stock units linked to DEEP FISSION, INC. (FISN). Each unit corresponds to one share of common stock, subject to vesting conditions.

When do the 19,156 restricted stock units for FISN vest?
The 19,156 restricted stock units vest on July 20, 2027. Vesting is contingent on the holder continuing to provide service to DEEP FISSION, INC. through that vesting date.

How many DEEP FISSION, INC. (FISN) RSUs does GLANVILLE THOMAS S hold after this Form 4?
After the reported transaction, GLANVILLE THOMAS S directly holds 19,156 restricted stock units. These units each represent a right to receive one share of DEEP FISSION, INC. common stock upon vesting.

What was the transaction price per restricted stock unit in the FISN Form 4?
The reported transaction price per restricted stock unit was $0.0000. This reflects a grant or award of equity compensation rather than an open-market purchase of DEEP FISSION, INC. shares.

Is the FISN Form 4 transaction a buy or a sale of shares?
The Form 4 reports an acquisition via grant of restricted stock units, not a market buy or sale. It reflects an equity award to director GLANVILLE THOMAS S, increasing his RSU holdings.
SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
GLANVILLE THOMAS S
(Last)(First)(Middle)
C/O DEEP FISSION, INC.
2001 ADDISON ST., SUITE 300
(Street)
BERKELEY CALIFORNIA 94704
(City)(State)(Zip)
UNITED STATES
(Country)		2. Issuer Name and Ticker or Trading Symbol
DEEP FISSION, INC. [ FISN ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/23/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Restricted Stock Unit$007/23/2026A19,156 (1) (1)Common Stock19,156$019,156D
Explanation of Responses:
1. Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock upon vesting. The units vest on July 20, 2027, provided the holder continues to provide service through the vesting date.
/s/ Jon Gordon, as Attorney-in-Fact for Thomas S. Glanville07/27/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR