Arthur J. Gallagher & Co.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

Information Required In Proxy Statement

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. __ )

Filed by the Registrant x Filed by a Party other than the Registrant ☐

Check the appropriate box:

ARTHUR J. GALLAGHER & CO.

(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):

Message to Our Stockholders

Dear Fellow Stockholder,

On behalf of our Board of Directors, I invite you to attend our

2026 Annual Meeting of Stockholders. We will be conducting

our Annual Meeting virtually again this year. If you are not

able to attend, we encourage you to vote by proxy. These

proxy materials contain detailed information about the

matters on which we are asking you to vote. We hope you

will read these materials and then vote in accordance with

the Board’s recommendations. Your vote is very important

to us.

Financial Performance

We had another outstanding year in 2025. On a combined

basis, our core brokerage and risk management segments

produced total adjusted revenue 1 growth of 20.7% (to $13.7

billion) and adjusted EBITDAC 1 growth of 25.7% (to $4.8

billion). We achieved organic revenue growth of 6% in both

segments. We also executed on our acquisition strategy

completing 33 acquisitions representing $3.6 billion in

estimated total acquired annualized revenue. This includes

AssuredPartners, the largest acquisition in our history and

the largest acquisition in the history of the insurance

brokerage industry, which we completed during the third

quarter. We have made great progress on the integration of

AssuredPartners and the acquisition positions us to provide

even more value to clients and drive additional

organic growth.

Board of Directors

Our Board of Directors is comprised of a group of committed

and highly qualified individuals who care deeply about our

company and bring a diversity of experiences and

perspectives to our Board deliberations. Our directors’

diverse professional backgrounds, skill sets, independent

thought leadership and experience have been invaluable to

me and the management team in establishing our long-term

business strategy, executing on that strategy and managing

both short- and long-term risks facing the company.

After nearly 13 years of service, Sherry Barrat is retiring and

not standing for reelection to our Board. Sherry served as

Chair of the Compensation Committee for many years, and

her executive management experience and financial

expertise enabled her to provide valuable oversight during a

period of significant growth for the company. I want to

personally express my appreciation for her years of

dedicated service and contributions to our financial success.

Commitment to Stockholder Engagement

Our Board values the feedback and insights gained from our

engagement with stockholders. During the past year, in

addition to our regular discussions with stockholders

1 See Exhibit A for reconciliations of non-GAAP measures.

We had another outstanding year in 2025. On a combined basis, our core

brokerage and risk management segments produced total adjusted revenue1 growth of 20.7% (to $13.7 billion) and adjusted EBITDAC1 growth of 25.7% (to $4.8 billion). We also completed the acquisition of AssuredPartners, the largest acquisition in our history.

regarding our financial results, we engaged with

stockholders representing more than 50% of shares

outstanding on corporate governance, Board and

management succession, executive compensation and

sustainability matters. We are committed to including our

stockholders’ perspectives in our deliberations and we

believe that regular communication is necessary in order to

provide thoughtful and informed consideration of evolving

best practices in areas of focus for our stockholders.

Our Unique Culture

For nearly a century, we have proudly built a reputation of

trust and integrity with our clients and colleagues. Now, more

than ever, I believe that this culture and history of integrity is

a true competitive advantage and a key differentiator when

recruiting and retaining talent, attracting acquisition partners,

retaining our valued clients and winning new business.

Looking Ahead

We enter 2026 with excellent momentum. Our teams are

working hard to integrate the AssuredPartners acquisition. It

is exciting to watch new colleagues from AssuredPartners

and other acquisitions leverage our product offerings and

data and analytics capabilities to create additional value for

clients. Our M&A pipeline remains strong and, with

substantial free cash flow, we expect to continue executing

on our acquisition strategy. We are well positioned to have

another outstanding year in 2026.

On behalf of our Board of Directors, thank you for your

continued support. We look forward to welcoming you at

our 2026 Annual Meeting.

Notice of 2026 Annual

Meeting of Stockholders

Arthur J. Gallagher & Co.2850 Golf RoadRolling Meadows, Illinois 60008-4050

Dear Stockholder

We are pleased to invite you to the 2026 Annual Meeting of Stockholders of Arthur J. Gallagher & Co. (Gallagher or the company),

which will be held as a virtual meeting, conducted via live audio webcast, on May 12, 2026, at 9:00 AM CDT. At the meeting,

stockholders will vote on each item described below and we will transact such other business that properly comes before the meeting.

Voting Items

Stockholders of record at the close of business on March 16, 2026 are entitled to notice of and to vote at the Annual Meeting.

The applicable voting standard and the treatment of abstentions and “broker non-votes” for each of these items are set forth on

page 55 of the Proxy Statement. Stockholders may vote shares prior to the meeting by visiting www.proxyvote.com.

On the day of the Annual Meeting, stockholders of record as of the close of business on March 16, 2026, the record date, are

entitled to participate in and vote at the Annual Meeting. To participate in the Annual Meeting, including to vote and ask questions,

stockholders of record should go to the meeting website at www.virtualshareholdermeeting.com/AJG2026, enter the 16-digit control

number found on your proxy card or Notice of Internet Availability of Proxy Materials, and follow the instructions on the website. If your

shares are held in street name and your voting instruction form or Notice of Internet Availability of Proxy Materials indicates that you

may vote those shares through the www.proxyvote.com website, then you may access, participate in, and vote at the Annual Meeting

with the 16-digit access code indicated on that voting instruction form or Notice of Internet Availability of Proxy Materials. Otherwise,

stockholders who hold their shares in street name should contact their bank, broker or other nominee (preferably at least 5 days

before the Annual Meeting) and obtain a “legal proxy” in order to be able to attend, participate in or vote at the Annual Meeting.

Stockholders are encouraged to log in to the Annual Meeting website before the Annual Meeting begins. Online check-in will be

available approximately 10 minutes before the meeting starts. Additional information regarding the rules and procedures for

participating in the virtual Annual Meeting will be set forth in our meeting rules of conduct, which stockholders will be able to view

during the meeting.

We urge you to read the Proxy Statement for additional information concerning the matters to be considered at the Annual Meeting

and then vote in accordance with the Board’s recommendations. Your vote is very important to us.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON MAY 12, 2026:We are making this Notice of Annual Meeting, this Proxy Statement, our 2025 Annual Report, and the Notice of Internet Availability of Proxy Materials available on the Internet at www.materials.proxyvote.com/363576 and mailing copies of these proxy materials to certain stockholders on or about March 23, 2026.

Proxy Statement

Table of Contents

Forward-Looking Statements

Some of the statements in this proxy statement may be considered forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. We caution investors that these forward-looking statements are not guarantees of future performance, and are subject to certain risks and uncertainties that could cause actual results to differ materially. Factors that could cause our future performance and actual results or outcomes to differ, possibly materially, from those expressed in the forward-looking statements include, but are not limited to, those factors discussed in our 2025 Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q, and the other filings we make with the Securities and Exchange Commission. Accordingly, you should not place undue reliance on forward-looking statements, which speak only as of, and are based on information available to us on, the date of the applicable document. We do not undertake any obligation to update any forward-looking statements made in or release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this proxy statement, which speaks as of the date issued, or to reflect new information, future or unexpected events or otherwise, except as required by applicable law or regulation. The inclusion of forward-looking and other sustainability-related statements in this proxy statement is not an indication that these contents are necessarily material to investors or required to be disclosed in our filings with the SEC. In addition, historical, current and forward-looking sustainability-related statements may be used based on standards for measuring progress that are still developing, internal controls and processes that continue to evolve, and assumptions that are subject to change in the future.