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 ý

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

ý     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):

ý     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.

RT: https://x.com/RocketLab/status/1955783426776465644

Copy: $RKLB shareholders: WE NEED YOUR VOTE! Please vote your shares before August 27, 2025.

Here’s how: https://t.co/u7MMtbotzi

RT: https://x.com/RocketLab/status/1955783426776465644

Copy: super important, please vote your $RKLB shares.

$RKLB shareholders: WE NEED YOUR VOTE!

Rocket Lab has a number of proposals that need your vote by our Annual Shareholders’ Meeting on August 27, 2025.

Shareholders of record on July 9, 2025 can vote now for or against a number of proposals by the Rocket Lab Board of Directors. We encourage all shareholders to vote with the Rocket Lab Board’s recommendations on all matters.

Learn more: http://bit.ly/45iyYfk

Hi everyone. Longtime lurker, first time poster - here to encourage everyone to vote their shares ahead of Rocket Lab’s upcoming Annual Shareholder meeting next week, August 27.

A number of proposals are being put forward and it’s important to cast your vote!

More on $RKLB’s IR website: http://bit.ly/45iyYfk

$RKLB Shareholders: Voting ahead of our upcoming Annual Meeting in four easy steps:

1️⃣Go to http://proxyvote.com

2️⃣Enter your control #

3️⃣Vote YES

4️⃣Submit

ℹ️ Info about the vote: https://t.co/u7MMtbotzi

$RKLB Shareholders: Voting ahead of our upcoming Annual Meeting in four easy steps:

1️⃣Go to http://proxyvote.com

2️⃣Enter your control #

3️⃣Vote YES

4️⃣Submit

ℹ️ Info about the vote: https://t.co/u7MMtbotzi

Have you voted your $RKLB shares yet? Please do!

1️⃣Go to http://proxyvote.com

2️⃣Enter your control #

3️⃣Vote YES

4️⃣Submit

ℹ️ Info about the vote: https://t.co/u7MMtbotzi

 Last chance to have your voice count by voting your $RKLB shares ahead of our ASM!

1️⃣Go to http://proxyvote.com

2️⃣Enter your control #

3️⃣Vote YES

4️⃣Submit

ℹ️ Info about the vote: https://t.co/u7MMtbotzi

Starting to sound like a spambot here, but please vote your $RKLB shares!

1️⃣Go to http://proxyvote.com

2️⃣Enter your control #

3️⃣Vote YES

4️⃣Submit

Or head to $RKLB’s IR website for info on voting through your broker: Annual Shareholder Meeting | Rocket Lab Corporation