Quest Diagnostics Inc

Proxy Statement Pursuant to Section 14(a) of the

Filed by a Party other than the Registrant ☐

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

☐ Soliciting Material Pursuant to §240.14a-12

(Name of Registrant as Specified In Its Charter)

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

☐ 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.

Working together to create a healthier world, one life at a time

We enable optimal, proactive health decisions by providing high-quality and affordable diagnostic testing insights and services using our scale and extensive reach

• Collaborating with healthcare providers and partners to leverage our broad access

• Offering an industry-leading menu of testing and other services

• Leveraging our data assets and services to improve population health and enable value-based care

• Continuously improving our quality and efficiency by embracing innovative technologies, such as automation and artificial intelligence ("AI")

Who we serve: physicians, hospitals, patients and consumers, health plans, employers, emerging retail healthcare providers, government agencies, pharmaceutical companies, and other commercial clinical laboratories

Customer first, Care, Collaboration, Continuous improvement, Curiosity

Notice of 2026 Annual Meeting of Stockholders

It is my pleasure to invite you to attend Quest Diagnostics' 2026 Annual Meeting of Stockholders (the "Annual Meeting"). At the Annual Meeting, stockholders will vote on the following, in addition to any other business as may properly come before the Annual Meeting or any adjournment or postponement thereof:

• to approve, on an advisory basis, the executive compensation disclosed in the accompanying proxy statement;

• to ratify the appointment of our independent registered public accounting firm for 2026; and

• to consider a stockholder proposal, as described in the accompanying proxy statement, if properly presented at the Annual Meeting.

Attendance at the Annual Meeting is limited to stockholders at the close of business on March 23, 2026, or their duly appointed proxy holder.

We enclose our proxy statement, our Annual Report and a proxy card; distribution of these materials is scheduled to begin on April 6, 2026. Your vote is very important. We urge you to submit your proxy even if you plan to attend the Annual Meeting. Most stockholders may submit a proxy via mail, telephone or the Internet. Instructions on how to submit your proxy are included with your proxy card and these proxy materials. Please submit your proxy promptly.

Thank you for your continued support of Quest Diagnostics.

This summary highlights information contained elsewhere in this proxy statement. This summary does not contain all of the information that you should consider, and you should read the entire proxy statement carefully before voting.

To approve, on an advisory basis, the compensation of our named executive officers disclosed in our Proxy Statement

To ratify the selection of PricewaterhouseCoopers LLP as our independent registered public accounting firm for 2026

To consider a stockholder proposal regarding an independent board chairman, if properly presented at the Annual Meeting

Stockholder proposals submitted pursuant to SEC Rule 14a-8 must be received by Quest Diagnostics Incorporated ("Quest Diagnostics,"the"Company," "we"or"our") by December 7, 2026.

Notice of stockholder proposals outside of SEC Rule 14a-8, including nominations (other than proxy access nominations) for the Board of Directors (the "Board"), must be received by the Company no earlier than January 20, 2027 and no later than February 19, 2027 and must comply with the requirements set forth in our by-laws. In addition to the requirements set forth in our by-laws, stockholders who intend to solicit proxies for nominations for election to the Board other than the Company's nominees in reliance on the universal proxy rules (Rule 14a-19 under the Securities Exchange Act of 1934, as amended (the "Exchange Act")) must also comply with the additional requirements of Rule 14a-19.

Notice of proxy access director nominations must be received by the Company no earlier than November 7, 2026 and no later than December 7, 2026.

The following table provides summary information about our director nominees.

Retired Executive Vice President and Chief Information Officer,

Chairman, Chief Executive Officer and President, Quest Diagnostics Incorporated

Head of the Division of Solid Tumor Oncology, Memorial Sloan Kettering Cancer Center

Retired Chief Financial Officer and Group Vice President of Toyota Motor North America, Inc.

Cofounder/Partner, Guidon Partners LLC and Retired CEO, Blue Cross and Blue Shield of Tennessee

Non-Executive Chairman of WNS (Holdings) Limited

Founder, Denise Morrison & Associates and Retired President and CEO, Campbell Soup Company

Retired Senior Vice President and Chief Financial Officer, E.I. du Pont de Nemours and Company