Rocket Lab Corp

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant☒

Filed by a Party other than the Registrant☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☒ Definitive Proxy Statement

☐ Definitive Additional Materials

☐ Soliciting Material Pursuant to Section 240.14a-12.

ROCKET LAB CORPORATION

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required.

☐ Fee paid previously with preliminary materials.

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

3881 McGowen Street

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON MAY 20, 2026

To Our Stockholders:

You are invited to attend the Annual Meeting of Stockholders (“Annual Meeting”) of Rocket Lab Corporation (the “Company”) to be held on Wednesday, May 20, 2026, beginning at 1:30 p.m. Pacific Daylight Time. The Annual Meeting will be a virtual meeting that will be conducted via live webcast. You will be able to attend the Annual Meeting online and submit your questions during the meeting by visitingwww.virtualshareholdermeeting.com/rklb2026 and entering your 16-digit control number included in your Notice of Internet Availability of Proxy Materials, on your proxy card or on the instructions that accompanied your proxy materials.

At the Annual Meeting, you are asked to consider and act upon the following proposals:

(1)To elect the one Class II director nominee named in the proxy statement to our Board of Directors;

(2)To ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026;

(3)To approve, on a non-binding advisory basis, the compensation of our named executive officers disclosed in the accompanying proxy statement;

(4)To approve a subsidiary merger to eliminate the recently added pass-through voting provision that requires approval by both the Company and the Company’s stockholders prior to certain actions being taken by or at Rocket Lab USA, Inc., the Company’s wholly owned subsidiary; and

(5)To transact such other business as may properly be brought before the meeting or any adjournment, continuance or postponement thereof at the direction of the Board of Directors (or an authorized committee of the Board).

Each of the matters to be acted upon at the meeting are more fully described in our proxy statement.

The record date for the Annual Meeting is March 30, 2026. Only stockholders of record at the close of business on that date may vote at the Annual Meeting or any adjournment, continuance or postponement thereof. To facilitate voting, internet and telephone voting are available. The instructions for voting are on the proxy card. If you hold your shares through a bank, broker or other holder of record, please follow the voter instructions you received from the holder of record.

Please carefully review the proxy statement and then complete and sign your proxy and return it promptly. If you attend the virtual meeting and decide to vote during the meeting, you may withdraw your proxy by voting at the meeting.

YOUR VOTE IS IMPORTANT.

All stockholders will have the ability to access the proxy materials on the website referred to in this Notice or request to receive a printed set of the proxy materials. Instructions on how to access the proxy materials over the internet or to request a printed copy may be found in the Notice. The Notice is being mailed to stockholders commencing on or about April 6, 2026. Please act as soon as possible to vote your shares whether or not you intend on attending the Annual Meeting.

By Order of the Board of Directors

Arjun L. Kampani

Senior Vice President, General Counsel and Secretary

April 6, 2026

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be held on:May 20, 2026 The Notice of Annual Meeting, Proxy Statement and our Annual Report are available electronically at www.proxyvote.com