System1 (SST) Form 4: Officer withheld 282 shares for taxes

System1, Inc. (SST) reported an insider transaction by Chief People Officer Elizabeth Sestanovich.

Rhea-AI Filing Summary

System1, Inc. (SST) reported an insider transaction by Chief People Officer Elizabeth Sestanovich. On 10/15/2025, 282 shares of Class A Common Stock were withheld at $7.94 per share to satisfy tax obligations upon the vesting of 670 RSUs, coded “F” (tax withholding).

Following the transaction, she beneficially owned 60,035 shares directly. This figure includes 44,100 unvested RSUs, as noted in the footnotes.

Insights

Equity Compensation & Insider Filings Analyst

Routine tax withholding on RSU vesting; neutral signal.

The filing shows a Code F transaction: 282 shares withheld at $7.94 on 10/15/2025 to cover taxes from the vesting of 670 RSUs. Code F indicates the issuer withheld shares, not an open-market sale by the insider.

Post-transaction beneficial ownership is 60,035 shares, including 44,100 unvested RSUs. This is a standard administrative event tied to equity compensation mechanics and does not by itself indicate a change in sentiment.

Insider Trade Summary

Exercise Price or Tax Liability: 282 shares

Exercise Price or Tax Liability 1 txn

Insider Sestanovich Elizabeth

Role Chief People Officer

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Class A Common Stock	282	$7.94	$2K

Holdings After Transaction: Class A Common Stock — 60,035 shares (Direct)

Footnotes (2)

1. F1. Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 282 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.
2. F2. Includes 44,100 unvested RSUs.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did SST’s insider transaction disclose on the Form 4?

282 shares were withheld at $7.94 on 10/15/2025 to cover taxes upon the vesting of 670 RSUs (Code F).

Who was the reporting person in SST’s Form 4 filing?

Chief People Officer Elizabeth Sestanovich.

How many shares does the insider beneficially own after the transaction?

She beneficially owned 60,035 shares directly after the transaction.

Does the reported ownership include unvested awards?

Yes. It includes 44,100 unvested RSUs, per the footnotes.

What does Transaction Code F mean in this context?

Code F indicates share withholding to pay taxes related to an award vesting, not an open-market sale.

What security class was involved in the transaction?

Class A Common Stock of System1, Inc. (SST).

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

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Accepted by SEC EDGAR 10/17/2025 - 07:09 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED 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^*

Sestanovich Elizabeth

(Last) (First) (Middle)

4235 REDWOOD AVE

(Street)

LOS ANGELES CA 90066

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
System1, Inc. [ SST ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief People Officer

3. Date of Earliest Transaction (Month/Day/Year)
10/15/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	10/15/2025		F		282(1)	D	$7.94	60,035(2)	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 282 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

2. Includes 44,100 unvested RSUs.

Remarks:

	/s/ Daniel Weinrot, Attorney-in-Fact for Elizabeth Sestanovich	10/17/2025
	** Signature of Reporting Person	Date
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.