Additional Proxy Soliciting Materials (Form DEFA14A)

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Preliminary Proxy Statement

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

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Definitive Proxy Statement

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Definitive Additional Materials

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Soliciting Material Under §240.14a-12

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No fee required

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Fee paid previously with preliminary materials

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

P.O. BOX 8016, CARY, NC 27512-9903

Your vote
matters!

Important Notice Regarding the Availability of Proxy Materials for the Stockholders Meeting to be held on April 27, 2026 For Stockholders of record as of March 2, 2026

To order paper materials, use one of the

following methods.

Kirby Corporation

Annual Meeting of Stockholders

Monday, April 27, 2026 10:00 AM, Central Daylight Time

55 Waugh Drive, Suite 1100 Houston, TX 77007

For a convenient way to view proxy materials, including the Notice of the 2026 Annual Meeting, Proxy Statement and the Company's Annual Report, VOTE, and obtain directions to attend the meeting go to www.proxydocs.com/KEX.

Internet:
www.investorelections.com/KEX

Call:

1-866-648-8133

Email:
[email protected]

* If requesting material by e-mail, please send a blank e-mail with the 12 digit control number (located below) in the subject line. No other requests, instructions OR other inquiries should be included with your e-mail requesting material.

To vote your proxy while visiting this site, you will need the 12 digit control number in the box below.

This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. This is not a ballot. You cannot use this notice to vote your shares. We encourage you to access and review all of the important information contained in the proxy materials before voting.

Under United States Securities and Exchange Commission rules, proxy materials do not have to be delivered in paper. Proxy materials can be distributed by making them available on the internet.

If you want to receive a paper or e-mail copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. In order to receive a paper package in time for this year's meeting, you must make this request on or before April 17, 2026.

Have the 12 digit control number located in the box above available when you access the website and follow the instructions.

SEE REVERSE SIDE FOR FULL AGENDA

Kirby Corporation Annual Meeting of Stockholders

THE BOARD OF DIRECTORS RECOMMENDS A VOTE:

FOR ON PROPOSALS 1, 2, 3, 4 AND 5

PROPOSAL

1.

Election of three Class I directors

1.01 Richard J. Alario

1.02 Tracy A. Embree

1.03 David W. Grzebinski

2.

Ratification of the Audit Committee's selection of KPMG LLP as Kirby's independent registered public accounting firm for 2026

3.

Advisory vote on the approval of the compensation of Kirby's named executive officers

4.

Approval of Amendment of the 2005 Stock and Incentive Plan

5.

Approval of Amendment of the 2000 Nonemployee Director Stock Plan