System1 executive has 7,058 shares withheld for taxes

System1, Inc. reported that Chief People Officer Elizabeth Sestanovich had 7,058 shares of Class A common stock withheld on July 15, 2026 to satisfy tax obligations on the vesting of 13,870 restricted stock units (RSUs).

Accepted by SEC EDGAR 07/17/2026 - 06:08 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

System1, Inc. reported that Chief People Officer Elizabeth Sestanovich had 7,058 shares of Class A common stock withheld on July 15, 2026 to satisfy tax obligations on the vesting of 13,870 restricted stock units (RSUs). After this tax-withholding disposition, she directly held 51,890 shares, including 28,140 unvested RSUs.

Insider Trade Summary

Tax Withholding: 7,058 shares

Tax Withholding 1 txn

Insider Sestanovich Elizabeth

Role Chief People Officer

Type	Security	Shares	Price	Value
Tax Withholding	Class A Common Stock F1, F2	7,058	$2.60	$18K

Holdings After Transaction: Class A Common Stock — 51,890 shares (Direct)

Footnotes (2)

1. F1. Upon the vesting of 13,870 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 7,058 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.
2. F2. Includes 28,140 unvested RSUs.

Key Figures

Shares withheld for taxes: 7,058 shares Per-share value for withholding: $2.6000 per share Shares held after transaction: 51,890 shares +2 more

5 metrics

Shares withheld for taxes 7,058 shares Class A common stock withheld for tax obligation on July 15, 2026

Per-share value for withholding $2.6000 per share Value applied to the 7,058 withheld shares

Shares held after transaction 51,890 shares Direct Class A common stock holdings following the disposition

RSUs vested 13,870 RSUs Restricted stock units that vested and triggered the tax withholding

Unvested RSUs included in holdings 28,140 unvested RSUs Unvested RSUs included in post-transaction direct holdings

Key Terms

restricted stock units, tax withholding obligation, unvested RSUs

3 terms

restricted stock units financial

"Upon the vesting of 13,870 restricted stock units ("RSUs") previously granted"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding obligation financial

"withheld 7,058 shares to cover the reporting person's tax withholding obligation"

unvested RSUs financial

"Includes 28,140 unvested RSUs."

FAQ

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

What insider transaction did System1 (SST) report for Elizabeth Sestanovich?

System1 (SST) reported that Chief People Officer Elizabeth Sestanovich had 7,058 shares of Class A common stock withheld on July 15, 2026 to cover taxes on vesting RSUs, leaving her with 51,890 shares directly held after the transaction.

How many System1 (SST) shares were withheld for taxes in this Form 4?

The company withheld 7,058 shares of System1 (SST) Class A common stock to satisfy Elizabeth Sestanovich’s tax withholding obligation related to vesting restricted stock units, at a reported value of $2.60 per share for this tax-withholding disposition.

What triggered the tax withholding reported for System1 (SST)’s CPO?

The tax withholding arose upon the vesting of 13,870 restricted stock units (RSUs) previously granted to Elizabeth Sestanovich. When these RSUs vested, 7,058 shares were withheld by the company to cover her associated tax withholding obligation on that vesting event.

How many unvested System1 (SST) RSUs does the CPO still hold after this filing?

After the reported transaction, Elizabeth Sestanovich’s holdings include 28,140 unvested RSUs. This figure is specifically identified in the footnotes as part of her reported direct holdings following the tax-withholding disposition tied to the vesting of other RSUs.

Was the System1 (SST) insider transaction under a Rule 10b5-1 plan?

The Form 4 does not indicate that the transaction was executed under a Rule 10b5-1 trading plan; the document-level checkbox affirming such a plan is not marked, and the footnotes describe the event solely as tax withholding on vesting RSUs.

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

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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 CALIFORNIA 90066

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/15/2026

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

X	Form 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)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	07/15/2026		F		7,058(1)	D	$2.6	51,890(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 13,870 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 7,058 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

2. Includes 28,140 unvested RSUs.

Remarks:

	/s/ Daniel Weinrot, Attorney-in-Fact for Elizabeth Sestanovich	07/17/2026
	** 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.
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)