As filed with the Securities and Exchange Commission on October 17, 2025. Registration No. 333-290243 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 1 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 MOMENTUS INC. (Exact Name of Registrant as Specified in Its Charter) (State or Other Jurisdiction of Incorporation or Organization) Delaware 3714 84-1905538 (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification Number) 390 ...