SCHEDULE 13G/A 0000902664-24-001620 0001771944 XXXXXXXX LIVE 2 Common Stock, par value $1.00 per share 03/31/2025 0001333274 MERCER INTERNATIONAL INC. 588056101 700 WEST PENDER STREET SUITE 1120 VANCOUVER A1 V6C 1G8 Rule 13d-1(b) Boundary Creek Advisors LP DE 0.00 3981773.00 0.00 3981773.00 3981773.00 N 6.0 IA PN Peter Greatrex X1 0.00 3981773.00 0.00 3981773.00 3981773.00 N 6.0 HC IN MERCER INTERNATIONAL INC. Suite 1120, 700 West Pender Street Vancouver, British Columbia Canada V6C 1G8 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 $1.00 per share (the "Common Stock") of Mercer International Inc. (the "Company") 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 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 66,870,774 shares of Common Stock outstanding as of February 18, 2025, as reported in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the Securities and Exchange Commission on February 20, 2025. 6.0% 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