VACQU Vector Acquisition Corporation

Filed Pursuant to Rule 424(b)(3)
Registration Nos. 333-259797 and 333-257440

PROSPECTUS SUPPLEMENT NO. 14

(to Prospectus dated October 7, 2021)

Rocket Lab USA, Inc.

This prospectus supplement is being filed to update and supplement the information contained in the combined prospectus dated October 7, 2021 (as supplemented or amended from time to time, the “Prospectus”), which forms a part of our Registration Statements on Form S-1 (Registration Nos. 333-259797 and 333-257440). This prospectus supplement is being filed to update and supplement the information included or incorporated by reference in the Prospectus with the information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission (the “SEC”) on April 15, 2022 (the “Form 8-K”). Accordingly, we have attached the Form 8-K to this prospectus supplement.

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

Our common stock is listed on the Nasdaq Capital Market under the symbol “RKLB”. On April 14, 2022, the last reported sales price of our common stock was $8.42 per share.

We are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended, and, as such, have elected to comply with certain reduced disclosure and regulatory requirements.

Investing in our securities involves risks. See the section entitled “Risk Factors” beginning on page 9 of the Prospectus.

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued or sold under the Prospectus or determined if the Prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is April 15, 2022

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): April 15, 2022

Registrant’s telephone number, including area code (714) 465-5737

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

The Board of Directors of Rocket Lab USA, Inc., a Delaware corporation (the “Company”) has established June 23, 2022 as the date of the Company’s 2022 Annual Meeting of Stockholders (the “Annual Meeting”). The time and location of the Annual Meeting will be as set forth in the Company’s definitive proxy statement for the Annual Meeting. Because the date of the Annual Meeting has advanced by more than 30 days from the annual notice date previously provided to the stockholders, in accordance with Rule 14a–5(f) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), the Company is informing stockholders of such change.

Because the date of the Annual Meeting has advanced by more than 30 days from the annual notice date previously provided to the stockholders, a new deadline has been set for submission of proposals by stockholders of the Company pursuant to Rule 14a-8 under the Exchange Act. Stockholders of the Company who wish to have a proposal considered for inclusion in the Company’s proxy materials for the Annual Meeting pursuant to Rule 14a-8 under the Exchange Act must ensure that such proposal is received by the Company’s Secretary, at c/o Rocket Lab USA, Inc. 3881 McGowen Street, Long Beach, California 90808, on or before the close of business on April 25, 2022, which the Company has determined to be a reasonable time before it expects to begin to print and send its proxy materials. Additional requirements apply under the Company’s Amended and Restated Bylaws (the “Bylaws”) for stockholders who intend to include a proposal in the Company’s proxy statement and proxy card for the Annual Meeting pursuant to Rule 14a-8 under the Exchange Act. Any such proposal must also meet the requirements set forth in the rules and regulations of the Securities and Exchange Commission in order to be eligible for inclusion in the proxy materials for the Annual Meeting. The April 25, 2022 deadline also will apply in determining whether notice of a shareholder proposal is timely for purposes of exercising discretionary voting authority with respect to proxies under Rule 14a-4(c) of the Exchange Act.

In addition, because the date of the Annual Meeting has advanced by more than 30 days from the annual notice date previously provided to the stockholders, in accordance with the requirements contained in the Company’s Bylaws, stockholders of the Company who wish to bring business before the Annual Meeting outside of Rule 14a-8 of the Exchange Act or to nominate a person for election as a director must ensure that written notice of such proposal (including all of the information specified in the Company’s Bylaws) is received by the Company’s Secretary at the address specified above no later than the close of business on April 25, 2022, which is the 10th day following the date on which the public announcement of the date of such meeting is first made by this Current Report on Form 8-K. Any such proposal must meet the requirements set forth in the Company’s Bylaws in order to be brought before the Annual Meeting.