UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. )

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☐ 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 §240.14a-12

The Greenbrier Companies, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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Your Vote Counts! THE GREENBRIER COMPANIES, INC. 2024 Annual Meeting Vote by January 4, 2024 11:59 PM ET THE GREENBRIER COMPANIES, INC. ONE CENTERPOINTE DRIVE, STE 200 LAKE OSWEGO, OR 97035 V24979-P99541 You invested in THE GREENBRIER COMPANIES, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the shareholder meeting to be held on January 5, 2024. Get informed before you vote View the Notice and Proxy Statement and Annual Report/10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to December 22, 2023. If you would like to request a copy of the material(s) for this and/or future shareholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # Smartphone users Vote Virtually at the Meeting* Point your camera here and January 5, 2024 12:00 PM PST vote without entering a control number Virtually at: www.virtualshareholdermeeting.com/GBX2024 *Please check the meeting materials for any special requirements for meeting attendance. V1.2

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming shareholder meeting. Please follow the instructions on the reverse side to vote these important matters. Voting Items Board Recommends 1. Election of Directors: Nominees: 1a. Patrick J. Ottensmeyer For 1b. Lorie L. Tekorius For 1c. Kelly M. Williams For 2. Advisory approval of the compensation of the Company’s named executive officers. For 3. Advisory approval of the frequency of executive compensation vote. 1 Year 4. Approve an amendment and restatement of the 2014 Employee Stock Purchase Plan, as amended. For 5. Ratification of the appointment of KPMG LLP as the Company’s independent auditors for fiscal 2024. For NOTE: Such other business as may properly come before the meeting or any adjournment thereof. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Delivery Settings”. V24980-P99541