SCHEDULE 13G/A 0000902664-24-001619 0001771944 XXXXXXXX LIVE 1 Common Stock, par value $0.10 per share 03/31/2025 0001000623 Mativ Holdings, Inc. 808541106 100 NORTH POINT CENTER EAST SUITE 600 ALPHARETTA GA 30022-8246 Rule 13d-1(b) Boundary Creek Advisors LP DE 0.00 2820289.00 0.00 2820289.00 2820289.00 N 5.2 IA PN Includes 875,000 shares of Common Stock (as defined in Item 2(a)) underlying call options Peter Greatrex X1 0.00 2820289.00 0.00 2820289.00 2820289.00 N 5.2 HC IN Includes 875,000 shares of Common Stock underlying call options Mativ Holdings, Inc. 100 Kimball Place, Suite 600 Alpharetta, GA 30009 This statement is filed by: (i) Boundary Creek Advisors LP (the "Investment Manager"), a Delaware limited partnership, and the investment adviser to Boundary Creek Master Fund LP (the "Boundary Creek Fund"), with respect to the shares of common stock, par value $0.10 per share (the "Common Stock") of Mativ Holdings, Inc. (the "Company") directly held by (and underlying call options directly held by) the Boundary Creek Fund; and (ii) Mr. Peter Greatrex ("Mr. Greatrex"), the managing member of Boundary Creek Partners LLC, the general partner of the Investment Manager, with respect to the shares of Common Stock directly held by (and underlying call options directly held by) the Boundary Creek Fund. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." The filing of this statement should not be construed as an admission that any of the foregoing persons or any Reporting Person is, for the purposes of Section 13 of the Securities Exchange Act of 1934, the beneficial owner of the shares of Common Stock reported herein. The address of the business office of each of the Reporting Persons is 340 Madison Avenue, 12th Floor, New York, NY 10173. The Investment Manager is a Delaware limited partnership. Mr. Greatrex is a citizen of the United States. N IA HC The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 54,517,608 shares of Common Stock outstanding as of March 10, 2025, as reported in the Company's Definitive Proxy Statement on Schedule 14A filed with the Securities and Exchange Commission on March 21, 2025. 5.2% The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference. Y N See Item 2(a). The Boundary Creek Fund has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the shares of Common Stock reported herein. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. Boundary Creek Advisors LP /s/ David O'Mara 05/13/2025 Peter Greatrex /s/ Peter Greatrex 05/13/2025