X0202 SCHEDULE 13G/A 0000919574-26-003737 0001595082 XXXXXXXX LIVE 1 Class A Common Stock, par value $0.00001 per share 06/30/2026 0001781162 Momentus Inc. 60879E408 1762 AUTOMATION PARKWAY SAN JOSE CA 95131 Rule 13d-1(c) M.H. Davidson & Co. b NY 0.00 15471.00 0.00 15471.00 15471.00 N 0.08 PN Davidson Kempner Arbitrage, Equities & Relative Value LP b E9 0.00 834529.00 0.00 834529.00 834529.00 N 4.43 PN Davidson Kempner Capital Management LP b DE 0.00 850000.00 0.00 850000.00 850000.00 N 4.51 PN Anthony A. Yoseloff b X1 0.00 850000.00 0.00 850000.00 850000.00 N 4.51 IN Momentus Inc. 1762 Automation Parkway, San Jose, California 95131 This Statement is filed by each of the entities and persons listed below, all of whom together are referred to herein as the "Reporting Persons": (i) M.H. Davidson & Co., a New York limited partnership ("CO"). M.H. Davidson & Co. GP, L.L.C., a Delaware limited liability company ("CO GP"), is the general partner of CO and Davidson Kempner Liquid GP Topco LLC, a Delaware limited liability company, is the managing member of CO GP. DKCM (as defined below) is responsible for the voting and investment decisions of CO; (ii) Davidson Kempner Arbitrage, Equities and Relative Value LP, a Cayman Islands exempted limited partnership ("DKAERV"). Davidson Kempner Multi-Strategy GP II LLC, a Delaware limited liability company ("DKAERV GP"), is the general partner of DKAERV and Davidson Kempner Liquid GP Topco LLC, a Delaware limited liability company, is the managing member of DKAERV GP. DKCM is responsible for the voting and investment decisions of DKAERV; (iii) Davidson Kempner Capital Management LP, a Delaware limited partnership and a registered investment adviser with the U.S. Securities and Exchange Commission, acts as investment manager to each of CO and DKAERV ("DKCM"). DKCM GP LLC, a Delaware limited liability company, is the general partner of DKCM. The managing members of DKCM are Anthony A. Yoseloff, Conor Bastable, Morgan P. Blackwell, Patrick W. Dennis, Gabriel T. Schwartz, Zachary Z. Altschuler, Joshua D. Morris, Suzanne K. Gibbons, Gregory S. Feldman, Melanie Levine and James Li; and (iv) Anthony A. Yoseloff, through DKCM, is responsible for the voting and investment decisions relating to the Class A common stock, par value $0.00001 per share ("Class A Common Stock"), of Momentus Inc. (the "Company") held by CO and DKAERV. The address of the principal business office of each of the Reporting Persons is c/o Davidson Kempner Capital Management LP, 9 West 57th Street, 29th Floor, New York, NY 10019. (i) CO - a New York limited partnership (ii) DKAERV - a Cayman Islands exempted limited partnership (iii) DKCM - a Delaware limited partnership (iv) Anthony A. Yoseloff - United States Y 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 percentages set forth in this Schedule 13G are calculated based upon an aggregate of 18,835,815 shares of Class A Common Stock outstanding as of June 18, 2026, as reported in the Company's Prospectus filed pursuant to Rule 424(b)(5) filed with the Securities and Exchange Commission on June 18, 2026. 4.51% 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. N Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above 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. M.H. Davidson & Co. /s/ Anthony A. Yoseloff 08/14/2026 Davidson Kempner Arbitrage, Equities & Relative Value LP /s/ Anthony A. Yoseloff 08/14/2026 Davidson Kempner Capital Management LP /s/ Anthony A. Yoseloff 08/14/2026 Anthony A. Yoseloff /s/ Anthony A. Yoseloff 08/14/2026