Sec Form 4 Filing - Saintil Merline @ Rocket Lab USA, Inc. - 2022-09-06

FORM 4 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 Saintil Merline 2. Issuer Name and Ticker or Trading Symbol Rocket Lab USA, Inc. [ RKLB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ROCKET LAB USA, INC., 3881 MCGOWEN STREET 3. Date of Earliest Transaction (MM/DD/YY) 09/06/2022 (Street) LONG BEACH, CA90808 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 Common Stock 09/06/2022 M 362,386( 1 ) A 400,476( 3 ) D

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 Restricted Stock Units ( 4 ) 09/06/2022 M 362,386 ( 4 ) ( 4 ) Common Stock 362,386 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Saintil Merline C/O ROCKET LAB USA, INC. 3881 MCGOWEN STREET LONG BEACH, CA90808 X Signatures /s/ Merline Saintil 09/08/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents 120,795 shares of common stock issued on settlement of Restricted Stock Units ("RSUs") on September 6, 2022, and 241,591 RSUs subject to service-based vesting. ( 2 )Each RSU represents a contingent right to receive one share of the issuer's common stock upon settlement. ( 3 )Includes 120,795 shares of common stock issued on settlement of RSUs on September 6, 2022; 241,591 RSUs previously reported in Table II that remain subject to service-based vesting requirements described in note 4 below; and 38,090 RSUs previously reported on Table I subject to service-based vesting requirements. ( 4 )The RSUs are subject to both a service-based vesting condition and liquidity-based vesting condition. The liquidity-based vesting condition was waived by the Board for these RSUs on September 6, 2022. One-third of the RSUs satisfied the service-based vesting condition on August 22, 2022 and were settled for 120,795 shares of common stock on September 6, 2022, and the remaining two-thirds of the RSUs vest in eight substantially equal quarterly installments on each November 22nd, March 1st, May 22nd and August 22nd thereafter. As a result of the waiver of the liquidity-based vesting condition, the reporting person has elected to report the remaining unvested RSUs on Table I consistent with other service-based vesting RSU reporting.

Remarks: Exhibit 24 - Power of Attorney

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