Sec Form 3 Filing - GRIFFIN MICHAEL D @ Rocket Lab USA, Inc. - 2021-08-25

FORM 3 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 GRIFFIN MICHAEL D 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) 08/25/2021 (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

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 ( 1 ) ( 1 ) ( 1 ) Common Stock 608,256 D Earnout Rights (restricted stock units) ( 2 ) ( 2 ) ( 2 ) Common Stock 49,152 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GRIFFIN MICHAEL D C/O ROCKET LAB USA, INC. 3881 MCGOWEN STREET LONG BEACH, CA90808 X Signatures /s/ Robert M.P. Hurwitz, as Attorney-in-Fact for Michael D. Griffin 09/07/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each restricted stock unit ("RSU") represents a contingent right to receive one share of the issuer's common stock. The RSUs are subject to time-based vesting conditions, with 1/12 of the RSUs vesting every three months from July 30, 2020. The RSUs are also subject to liquidity-based vesting conditions, which will be satisfied upon the first to occur of (i) a sale event with respect to the issuer or (ii) the issuer's initial public offering, in either case, prior to the expiration date of July 30, 2027. ( 2 )Each earnout right represents a contingent right (based on the reporting person's ownership of RSUs) to receive one share of the issuer's common stock. The earnout rights vest upon the issuer's common stock achieving a closing price per share equal to or greater than $20.00 for a period of at least 20 trading days out of 30 consecutive trading days during the period commencing on the 90th day following August 25, 2021 and ending on the 180th day following August 25, 2021. If the earnout rights vest, the reporting person's RSUs will be adjusted to relate to an additional number of shares of the issuer's common stock equal to the number of earnout rights that vest. If the target closing stock price is not achieved during such period, the earnout rights will be forfeited.

Remarks: Exhibit 24 - Power of Attorney

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).

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