System1, Inc. — Director's Dealing 2025

Jul 30, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: System1, Inc. (SST)
CIK: 0001805833
Period of Report: 2025-07-28

Reporting Person: Sestanovich Elizabeth (Chief People Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-07-28	Class A Common Stock	F	135	$7.51	Disposed	20317	Direct
2025-07-29	Class A Common Stock	A	40000	—	Acquired	60317	Direct

Footnotes

F1: Upon the vesting of 375 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 135 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

F2: Includes 4,770 unvested RSUs.

F3: The Reporting Person was granted 40,000 restricted stock units ("RSUs") in connection with his continued employment with System1, Inc. ("SST"). Each RSU represents the right to receive one share of SST Class A Common Stock upon vesting. Subject to the continued employment of Ms. Sestanovich through the applicable vesting date, one-third of the RSUs will vest on July 15, 2026, and the remaining two-thirds will vest in 8 substantially equal quarterly installments on each quarterly anniversary thereafter.

F4: Includes 44,770 unvested RSUs.