SST · System1, Inc.

Upon the vesting of 17,995 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 9,156 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 36,515 unvested RSUs.

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.

Includes 28,140 unvested RSUs.

Upon the vesting of 17,338 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 6,022 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 35,176 unvested RSUs.

Upon the vesting of 13,954 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 6,124 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 28,308 unvested RSUs.

Mr. Kidambi was granted 35,300 restricted stock units ("RSUs"), which was fully vested on the date of grant. Each RSU represents the right to receive one share of SST Class A Common Stock upon vesting.

Includes 52,514 unvested RSUs.

The Reporting Person purchased 26,910 shares in a privately negotiated arm's length transaction from another existing holder of the Issuer's Class A common stock in a transaction that was not conducted through the exchange on which the Issuer's securities are listed.

Includes 53,352 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 341 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 42,010 unvested RSUs.

Upon the vesting of 754 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 331 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 42,262 unvested RSUs.

Upon the vesting of 838 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 301 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 52,514 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 341 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 54,510 unvested RSUs.

Upon the vesting of 625 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 258 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 53,352 unvested RSUs.

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.

Includes 42,680 unvested RSUs.

Upon the vesting of 469 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 231 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 43,016 unvested RSUs.

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.

Includes 55,180 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 377 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 43,055 unvested RSUs.

Upon the vesting of 754 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 371 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 43,485 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 377 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 55,555 unvested RSUs.

Upon the vesting of 837 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 345 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 53,977 unvested RSUs.

Upon the vesting of 625 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 263 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 54,814 unvested RSUs.

Upon the vesting of 375 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 158 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 43,725 unvested RSUs.

Upon the vesting of 375 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 214 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 56,225 unvested RSUs.

Upon the vesting of 469 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 235 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 44,239 unvested RSUs.

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.

Includes 44,100 unvested RSUs.

Upon the vesting of 837 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 352 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 55,439 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 382 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 56,600 unvested RSUs.

Upon the vesting of 754 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 377 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 44,708 unvested RSUs.

The price reported in Column 4 is a weighted average price. The shares were purchased in more than one transaction at prices ranging from $6.79 to $7.50, inclusive. The Reporting Person(s) undertake(s) to provide to the Issuer, any security holder, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

The price reported in Column 4 is a weighted average price. The shares were purchased in more than one transaction at prices ranging from $6.50 to $6.92, inclusive. The Reporting Person(s) undertake(s) to provide to the Issuer, any security holder, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

The price reported in Column 4 is a weighted average price. The shares were purchased in more than one transaction at prices ranging from $6.13 to $6.50, inclusive. The Reporting Person(s) undertake(s) to provide to the Issuer, any security holder, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

The price reported in Column 4 is a weighted average price. The shares were purchased in more than one transaction at prices ranging from $6.20 to $6.50, inclusive. The Reporting Person(s) undertake(s) to provide to the Issuer, any security holder, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Mr. Civantos' continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Mr. Horn continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Ms. Kazerani's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Ms. Kazerani continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Mr. Naidu's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Mr. Naidu continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Mr. Martire's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Mr. Martire continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Ms. Horn's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Ms. Horn continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Mr. Kumar's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Mr. Kumar continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Represents a grant of 15,000 restricted stock units ("RSUs) which convert into Class A Common Stock on a one-for-one basis, pursuant to the 2022 Incentive Award Plan of the Issuer in connection with Mr. Caswell's continued service as a member of its Board of Directors as of the close of business on the date of its annual shareholder meeting. The RSUs vest in four (4) substantially equal quarterly installments on each of September 15, 2025, December 15, 2025, March 15, 2026 and June 15, 2026 as long Mr. Caswell continues to serve as a Director of the Issuer through the applicable vesting dates.

Includes 15,000 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

The Reporting Person was granted 52,500 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 Mr. Weinrot 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.

Includes 57,270 unvested RSUs.

The Reporting Person was granted 50,000 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 Mr. Kidambi 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.

Includes 56,276 unvested RSUs.

These stock appreciation rights (the "SARs") were granted to the Reporting Person pursuant to the System1, Inc. 2024 Stock Appreciation Rights Plan, as amended (the "Plan") and a corresponding Stock Appreciation Rights Grant Notice and Award Agreement between System1, Inc. (the "Issuer") and the Reporting Person. The SARs reported on this Form 4 represent the right to receive (at the Issuer's discretion), upon exercise of the SARs by the Reporting Person, a payment in either (x) Class A Common Stock, par value $0.0001 per share ("Class A Common Stock") or (y) cash, in the amount equal to the number of shares of Class A Common Stock underlying the number of SARs being exercised multiplied by the excess of the fair market value of one share of Class A Common Stock on (i) the date the SARs are exercised, and (ii) $7.09, the Issuer's closing price on July 29, 2025 (the date the SARs were granted, the "Grant Date").

These Stock Appreciation Rights (the "SARs") were granted to the Reporting Person on July 29, 2025 under the System1, Inc. 2024 Stock Appreciation Rights Plan, as amended (the "Plan") and vest (i) 25% (or 5,000 SARs) upon the Issuer first achieving trailing twelve month Adjusted EBITDA ("TTM Adjusted EBITDA") of $50.0 million after the date of grant, (ii) 25% (or 5,000 SARs) upon the Issuer first achieving TTM Adjusted EBITDA of $55.0 million after the date of grant, (iii) 25% (or 5,000 SARs) upon the Issuer first achieving TTM Adjusted EBITDA of $60.0 million after the date of grant and (iv) 25% (or 5,000 SARs) upon the Issuer first achieving TTM Adjusted EBITDA of $65.0 million after the date of grant, in each case, subject to the terms of the Plan and an award agreement entered into between the Reporting Person and the Issuer pursuant to the Plan.

Represents the total number of SARs held by the Reporting Person after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

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.

Includes 44,770 unvested RSUs.

The Reporting Person was granted 337,500 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 Mr. Ursini 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.

Includes 337,500 unvested RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

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 Mr. Coppola 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.

Includes 45,462 unvested RSUs.

Upon the vesting of 469 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 206 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 5,462 unvested RSUs.

Upon the vesting of 625 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 224 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 6,276 unvested RSUs.

Upon the vesting of 375 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 191 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Includes 4,770 unvested RSUs.

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.

Includes 4,770 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 240 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Includes 5,145 unvested RSUs.

Upon the vesting of 837 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 300 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Includes 6,901 unvested RSUs.

Upon the vesting of 670 restricted stock units ("RSUs") previously granted to the reporting person, the Company withheld 341 shares to cover the reporting person's tax withholding obligation with respect to the vesting of such RSUs.

Represents the total number of shares held after the Issuer's completion of a 1-for-10 reverse stock split that occurred on June 11, 2025.

Includes 5,145 unvested RSUs.