System1 (SST) HR chief uses 211 shares for RSU tax withholding

Rhea-AI Filing Summary

System1, Inc. reported an insider transaction by Chief People Officer Elizabeth Sestanovich. When 375 previously granted restricted stock units vested, the company withheld 211 shares of Class A Common Stock at $4.18 per share to cover her tax withholding obligation. After this tax-related share withholding, she beneficially owns 59,289 shares, which include 42,680 unvested RSUs.

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

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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)
01/28/2026

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	01/28/2026		F		211(1)	D	$4.18	59,289(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 375 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 211 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

2. Includes 42,680 unvested RSUs.

Remarks:

	/s/ Daniel Weinrot, Attorney-in-Fact for Elizabeth Sestanovich	01/29/2026
	** 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.
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FAQ

What insider transaction did System1 (SST) report for its Chief People Officer?

The filing shows a tax-related share withholding, not an open-market trade. System1 withheld 211 shares of Class A Common Stock upon vesting of 375 RSUs granted to Chief People Officer Elizabeth Sestanovich to satisfy her tax withholding obligation.

What is transaction code F in the System1 (SST) Form 4 filing?

Transaction code F indicates shares were withheld to pay taxes on a stock award. Here, 211 shares of System1 Class A Common Stock were withheld when 375 RSUs vested for Chief People Officer Elizabeth Sestanovich.

How many System1 (SST) shares does Elizabeth Sestanovich own after this Form 4?

Following the reported transaction, Chief People Officer Elizabeth Sestanovich beneficially owns 59,289 shares of System1 Class A Common Stock. This total includes 42,680 unvested restricted stock units (RSUs), as specifically noted in the filing’s footnotes.

Did the System1 (SST) Form 4 report an open-market sale by the Chief People Officer?

No, the Form 4 reports a tax withholding transaction rather than an open-market sale. The company withheld 211 shares when 375 RSUs vested to cover Chief People Officer Elizabeth Sestanovich’s tax obligation on that vesting.

What type of security was involved in the System1 (SST) insider transaction?

The transaction involved Class A Common Stock of System1, Inc. These shares were tied to the vesting of previously granted restricted stock units (RSUs), with 211 shares withheld by the company for tax withholding purposes.

At what price were System1 (SST) shares valued for the tax withholding transaction?

The withheld shares were valued at $4.18 per share for the tax withholding event. A total of 211 shares of Class A Common Stock were withheld when 375 RSUs vested for Chief People Officer Elizabeth Sestanovich.