Sec Form 4/A Filing - Prime Movers Lab Fund I LP @ Momentus Inc. - 2022-02-14

FORM 4/A Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Prime Movers Lab Fund I LP 2. Issuer Name and Ticker or Trading Symbol Momentus Inc. [ MNTS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) P.O. BOX 12829 3. Date of Earliest Transaction (MM/DD/YY) 02/14/2022 (Street) JACKSON, WY83002 4. If Amendment, Date Original Filed (MM/DD/YY) 02/16/2022 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Class A Common Stock 02/14/2022 S 218,575 D $ 3.3661( 7 ) 15,859,885( 10 ) D( 1 )( 6 ) Class A Common Stock 02/14/2022 S 86,639 D $ 3.3661( 7 ) 6,286,561( 11 ) I Held by Momentus PML SPV 1 LP( 2 )( 6 ) Class A Common Stock 02/14/2022 S 13,847 D $ 3.3661( 7 ) 1,004,747( 11 ) I Held by Momentus PML SPV 2 LP( 3 )( 6 ) Class A Common Stock 02/14/2022 S 34,345 D $ 3.3661( 7 ) 2,492,049( 11 ) I Held by Momentus PML SPV 3 LP( 4 )( 6 ) Class A Common Stock 02/14/2022 S 13,594 D $ 3.3661( 7 ) 986,406 I Held by Prime Movers Growth Fund I LP( 5 )( 6 ) Class A Common Stock 02/15/2022 S 208,450 D $ 3.0093( 8 ) 15,651,435 D( 1 )( 6 ) Class A Common Stock 02/15/2022 S 82,626 D $ 3.0093( 8 ) 6,203,935( 11 ) I Held by Momentus PML SPV 1 LP( 2 )( 6 ) Class A Common Stock 02/15/2022 S 13,206 D $ 3.0093( 8 ) 991,541( 11 ) I Held by Momentus PML SPV 2 LP( 3 )( 6 ) Class A Common Stock 02/15/2022 S 32,754 D $ 3.0093( 8 ) 2,459,295( 11 ) I Held by Momentus PML SPV 3 LP( 4 )( 6 ) Class A Common Stock 02/15/2022 S 12,964 D $ 3.0093( 8 ) 973,442 I Held by Prime Movers Growth Fund I LP( 5 )( 6 ) Class A Common Stock 02/16/2022 S 388,909 D $ 2.6912( 9 ) 15,262,526 D( 1 )( 6 ) Class A Common Stock 02/16/2022 S 154,156 D $ 2.6912( 9 ) 6,049,779( 11 ) I Held by Momentus PML SPV 1 LP( 2 )( 6 ) Class A Common Stock 02/16/2022 S 24,638 D $ 2.6912( 9 ) 966,903( 11 ) I Held by Momentus PML SPV 2 LP( 3 )( 6 ) Class A Common Stock 02/16/2022 S 61,109 D $ 2.6912( 9 ) 2,398,186( 11 ) I Held by Momentus PML SPV 3 LP( 4 )( 6 ) Class A Common Stock 02/16/2022 S 24,188 D $ 2.6912( 9 ) 949,254 I Held by Prime Movers Growth Fund I LP( 5 )( 6 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Prime Movers Lab Fund I LP P.O. BOX 12829 JACKSON, WY83002 X Momentus PML SPV 1 LP P.O. BOX 12829 JACKSON, WY83002 X MOMENTUS PML SPV 2 LP P.O. BOX 12829 JACKSON, WY83002 X Momentus PML SPV 3 LP P.O. BOX 12829 JACKSON, WY83002 X Prime Movers Growth Fund I LP P.O. BOX 12829 JACKSON, WY83002 X Sloss Dakin C/O PRIME MOVERS LAB, P.O. BOX 12829 JACKSON, WY83002 X Signatures /s/ Jon Layman, Authorized Person on behalf of the General Partner of each Reporting Person 02/18/2022 Signature of Reporting Person Date Dakin Sloss /s/ Jon Layman, Attorney- in- fact 02/18/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Held by Prime Movers Lab Fund I LP ("PML"). Prime Movers Lab GP I LLC ("PML GP") is the general partner of PML. ( 2 )Held by Momentus PML SPV 1 LP ("PML SPV 1"). PML GP is the general partner of PML SPV 1. ( 3 )Held by Momentus PML SPV 2 LP ("PML SPV 2"). Prime Movers Lab GP II LLC ("PML GP II") is the general partner of PML SPV 2. ( 4 )Held by Momentus PML SPV 3 LP ("PML SPV 3"). PML GP II is the general partner of PML SPV 3. ( 5 )Held by Prime Movers Growth Fund I LP ("PM Growth"). Prime Movers Growth GP I LLC ("PM Growth GP") is the general partner of PM Growth. ( 6 )Dakin Sloss is the manager of PML GP, PML GP II and PM Growth GP, and may be deemed to beneficially own the securities held by PML, PML SPV 1, PML SPV 2, PML SPV 3 and PM Growth. Mr. Sloss disclaims any beneficial ownership of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein. ( 7 )The price of $3.3661 per share represents a weighted average of purchase prices ranging from $3.00 to $3.61 per share. The reporting person undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer, full information regarding the number of shares purchased or sold at each separate price. ( 8 )The price of $3.0093 per share represents a weighted average of purchase prices ranging from $2.96 to $3.12 per share. The reporting person undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer, full information regarding the number of shares purchased or sold at each separate price. ( 9 )The price of $2.6912 per share represents a weighted average of purchase prices ranging from $2.585 to $2.845 per share. The reporting person undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer, full information regarding the number of shares purchased or sold at each separate price. ( 10 )Amount includes 172,863 shares inadvertently omitted from the prior Form 4 due to a clerical error. ( 11 )This amendment is being filed to correct a technical error that caused the omission of Momentus PML SPV 1 LP, Momentus PML SPV 2 LP, and Momentus PML SPV 3 LP as reporting persons.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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