Quest Diagnostics 10-K 2025-12-31

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934

For the Fiscal Year Ended December 31, 2025

Or

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to __________

Commission File Number 001-12215

Quest Diagnostics Incorporated

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes X No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act.

Yes No X

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes X No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Yes X No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. [☐ ]

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. [☒]

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. [☐]

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). [☐]

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No X

As of June 30, 2025, the aggregate market value of the approximately 112 million shares of voting and non-voting common equity held by non-affiliates of the registrant was approximately $20.0 billion, based on the closing price on such date of the registrant's Common Stock on the New York Stock Exchange.

As of February 2, 2026, there were outstanding 109,866,320 shares of the registrant’s common stock, $.01 par value.

Such Proxy Statement, except for the portions thereof which have been specifically incorporated by reference, shall not be deemed “filed” as part of this report on Form 10-K.

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INTRODUCTION

Quest Diagnostics works across the healthcare ecosystem to create a healthier world, one life at a time. We provide diagnostic insights from the results of our laboratory testing to empower people, physicians, and organizations to take action to improve health outcomes. Derived from one of the world's largest databases of de-identifiable clinical lab results, our diagnostic insights reveal new avenues to identify and treat disease, inspire healthy behaviors and improve healthcare management. In the right hands and with the right context, our diagnostic insights can inspire actions that transform lives and create a healthier world.

The patients we serve annually comprise approximately one-third of the adult population of the United States, and over a three-year period, we serve approximately one-half of the adult population of the United States. We estimate that annually we serve approximately half of the physicians and half of the hospitals in the United States.

The Quest Way

We operate our business and achieve our goals according to a clear set of principles we call “The Quest Way,” which consists of the following:

• Our Purpose, or why we exist, is to work together to create a healthier world, one life at a time.

• Our Strategy, or how we grow, is to provide solutions that serve the evolving needs of our customers, based on our high quality, innovative, convenient and affordable services.

• Our Culture, or how we work, is powered by what we call the “5Cs”: customer first, collaboration, care, continuous improvement, and curiosity.

We play a critical role in healthcare decisions for customers across the healthcare ecosystem, including physicians, hospitals, patients and consumers, health plans, government agencies, employers, retailers, pharmaceutical companies and insurers. We believe The Quest Way is aligned with the triple aim of healthcare of improving medical quality and the patient experience while reducing the overall cost of care.

We believe our employees are critical to our success, and we continually strive to create an environment that allows them to contribute to our goal of creating a healthier world. We are focused on delivering services that help improve the physician and healthcare provider experience to enable us and them to deliver high quality, effective and affordable care to patients. We provide a number of innovative ways for patients to access services from us, including consumer-initiated services offered through QuestHealth.com, which provides a high quality, self-directed option with physician oversight for individuals to gain insights into their health.

During 2025, we generated net revenues of $11.0 billion. Additional financial information concerning Quest Diagnostics for each of the years ended December 31, 2025, 2024 and 2023 is included in “Management's Discussion and Analysis of Financial Condition and Results of Operations” in Part II, Item 7 and our consolidated financial statements and notes thereto in “Financial Statements and Supplementary Data” in Part II, Item 8.

Quest Diagnostics was incorporated in Delaware in 1990; its predecessor companies date back to 1967. We conduct business through our headquarters in Secaucus, New Jersey, and our laboratories, patient service centers, offices and other facilities around the United States and in selected locations outside the United States. Unless the context otherwise requires, the terms “Quest Diagnostics,” “Quest,” the “Company,” “we” and “our” mean Quest Diagnostics Incorporated and its consolidated subsidiaries.

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OUR STRATEGY

Our strategy aims to achieve two key goals: generate growth and optimize our operating efficiency. Our growth strategy focuses on continually developing solutions to meet the evolving needs of our customers. We help people make the best decisions to improve health by providing high quality, innovative, convenient and affordable diagnostic testing insights and services using our scale and extensive reach. We drive growth by:

• offering an industry-leading menu of testing and other services;

• collaborating with healthcare providers and partners to leverage our broad access;

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

• continuously improving our quality and efficiency by leveraging the Quest Management System and by embracing innovative technologies, such as automation and artificial intelligence ("AI").

Our growth strategy is focused on our primary customer channels – physicians, hospitals, patients and consumers – supported by Advanced Diagnostics™ (defined below), strategic acquisitions, and continuous quality improvement.

Physicians

We serve approximately half the physicians in the United States each year. We serve virtually all types of physicians from primary care physicians and internists to specialists, including rheumatologists, cardiologists, neurologists, and obstetricians/gynecologists. We also serve physicians associated with accountable care organizations (“ACOs”), and Federally Qualified Health Centers (“FQHCs”). Physicians determine which laboratory to recommend or use based on a variety of factors, but we believe that we provide the most attractive service offering in the industry, including a comprehensive test menu, innovative test offerings, a positive customer experience, deep medical and scientific expertise, high quality, leading access and distribution, and data-powered integrated information-technology solutions. Large physician practices value our ability to standardize services on a national or regional scale.

Hospitals

We believe that the market challenges faced by hospitals, including continued consolidation, price transparency, cost and utilization pressure, evolving healthcare payment models, capital needs, changing technology and limited resources, provide us with an opportunity to partner with them as they consider more effective ways to implement their laboratory testing strategy and drive demand for our expertise and services.

We serve approximately half the hospitals in the United States each year in many ways, including:

• Serving as a hospital lab’s laboratory. In 2025, we generated approximately $1.2 billion in revenue from “reference testing,” where we perform testing that hospitals do not perform in their own in-hospital labs.

• Helping hospitals operate their labs more efficiently. In 2025, our Collaborative Lab Solutions (formerly known as Professional Laboratory Services) offering generated approximately $800 million in revenues and management fees supporting hospitals in the operation of their own labs. Our key Collaborative Lab Solutions offerings include lab management outsourcing, test menu optimization and spend consolidation, supply chain management, and providing advanced data solutions.

• Acquiring outreach lab operations from hospitals. Quest looks for opportunities to acquire assets of outreach lab operations from hospitals whose in-house labs have expanded from supporting in-patients to supporting out-patients and ambulatory patients who see physicians that may or may not be employed or otherwise affiliated with the hospitals.

We also have joint venture arrangements with leading hospitals and health systems. These joint venture arrangements, which provide diagnostic information services for affiliated and nonaffiliated hospitals and clinicians and other local healthcare providers, serve as our principal facilities in their service areas. Typically, we have either a majority ownership interest in, or day-to-day management responsibilities for, our joint venture relationships.

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**Patients and C

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You should carefully consider all of the information set forth in this Report, including the following risk factors, before deciding to invest in any of our securities. The risks below are not the only ones that we face. Additional risks not presently known to us, or that we presently deem immaterial, may also negatively impact us. Our business, consolidated financial condition, revenues, results of operations, profitability, cash flows or reputation, or the price of our common stock, could be materially impacted by any of these factors.

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RISKS RELATED TO OUR BUSINESS

The U.S. healthcare system continues to evolve, and medical laboratory testing market fundamentals are changing, and our business could be adversely impacted if we fail to adapt.

The U.S. healthcare system continues to evolve. Significant change is taking place in the healthcare system, including as discussed above under the heading "The Clinical Testing Industry." For example, value-based reimbursement is increasing (e.g., UnitedHealthcare's Preferred Lab Network) and CMS has set goals for value-based reimbursement to be achieved by 2030. Patients are encouraged to take increased interest in and responsibility for, and often are bearing increased responsibility for payment for, their healthcare. Healthcare industry participants are evolving and consolidating. Healthcare services increasingly are being provided by non-traditional providers (e.g., physician assistants), in non-traditional venues (e.g., retail medical clinics, urgent care centers) and using new technologies (e.g., telemedicine, digital pathology). Utilization of the healthcare system is being influenced by several factors and may result in a decline in the demand for diagnostic information services. In addition, we believe that clinical testing market fundamentals are changing. The regulatory environment related to reimbursement rates for clinical laboratory tests under Medicare are in flux and we also believe that health plans and consumers increasingly are focusing on driving better value in laboratory testing services. We expect that the evolution of the healthcare industry will continue, and that industry change is likely to be extensive.

In addition, the diagnostic information services industry is faced with potential changes in government regulations that could impact patient access to healthcare. We expect that the evolution of the healthcare industry will continue, and that industry change is likely to be extensive.

The clinical testing business is highly competitive, and if we fail to provide an appropriately priced level of service or otherwise fail to compete effectively it could have a material adverse effect on our revenues and profitability.

The clinical testing business remains a fragmented and highly competitive industry. We primarily compete with three types of clinical testing providers: other commercial clinical laboratories, including smaller regional and local commercial clinical laboratories and specialized advanced laboratories, hospital-affiliated laboratories and physician-office laboratories. We also compete with other providers, including anatomic pathology practices, large physician group practices and providers of consumer-initiated testing. Hospitals and companies that directly or indirectly employ or manage physicians also present a competitive threat to our business. Hospitals generally maintain on-site laboratories to perform testing on their patients (inpatient or outpatient). In addition, many hospitals compete with commercial clinical laboratories for outreach (non-hospital patients) testing. Hospitals may seek to leverage their relationships with community clinicians and encourage the clinicians to send their outreach testing to the hospital's laboratory. As a result of this affiliation between hospitals and community clinicians, we compete against hospital-affiliated laboratories primarily based on quality and scope of service as well as pricing. There has been a trend of hospitals acquiring physician practices, increasing the percentage of physician practices owned by hospitals. Increased hospital ownership of physician practices may enhance clinician ties to hospital-affiliated laboratories, even encouraging or requiring the practices they own to refer testing to the hospital's laboratory, strengthening their competitive position further. The formation of ACOs and their approach to contracts with healthcare providers also may increase competition to provide diagnostic information services. In addition, new players have recently started to provide clinical lab testing services (e.g., employers; government agencies).

The diagnostic information services industry also is faced with changing technology and new product introductions. Competitors may compete using advanced technology, including technology that enables more convenient or cost-effective testing (e.g., technology enabled by AI). Digital pathology is an example of this. Competitors also may compete on the basis of new service offerings. Competitors also may offer new testing services that can be performed outside of a commercial clinical laboratory, such as point-of-care testing that can be administered by physicians in their offices, complex testing that can be performed by hospitals in their own laboratories, and home testing that can be carried out without requiring the services of providers like us.

Government payers, such as Medicare and Medicaid, have taken steps to reduce the utilization and reimbursement of healthcare services, including clinical testing services.

We face efforts by government payers to reduce utilization of and reimbursement for diagnostic information services. One example of this is increased use of prior authorization requirements. We expect efforts to reduce reimbursements, to impose more stringent cost controls and to reduce utilization of clinical test services will continue.

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Pursuant to PAMA, reimbursement rates for many clinical laboratory tests provided under Medicare were reduced during 2018 - 2020. Unfortunately, by relying on laboratory reported data alone in 2017, CMS did not receive comprehensive and representative data needed to set Medicare rates that reflected the commercial market, as required under PAMA. Independent laboratories were overrepresented, and hospitals and physician office laboratories were underrepresented, making the first round of PAMA cuts excessive. The first three years of cuts greatly exceeded the original 10-year savings projections. Starting in 2020, Congress has repeatedly acted to delay PAMA implementation by delaying the next round of data reporting (2020-2026) and Medicare cuts (2021-2026). However, the structural flaws of PAMA still need to be addressed to mitigate future excessive cuts. Congress introduced legislation in 2025, the Results Act, which would reform PAMA and create a true market-based CLFS.

In addition, CMS has adopted policies limiting or excluding coverage for clinical tests that we perform. We also provide physician services that are reimbursed by Medicare under a physician fee schedule, which is subject to adjustment on an annual basis. Medicaid reimbursement varies by state and is subject to administrative and billing requirements and budget pressures.

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There are no unresolved SEC comments that require disclosure.

Risk Management and Strategy

The strength and resilience of our cybersecurity and data privacy programs are critical in maintaining the trust of our patients, customers, employees, shareholders, and other stakeholders. Securing our business information, customer, patient and employee data and IT systems is an important part of our overall risk management framework. We rely on IT systems, some of which are dependent on services provided by third parties, to provide data and other services, including diagnostic information services for patients, clinicians and healthcare organizations, clinical testing, test ordering and reporting, billing, customer service, logistics, commercial and operational data, human resources management, legal, finance and tax compliance, and other information and processes necessary to operate and manage our business.

We maintain comprehensive cybersecurity and data privacy programs that are designed to be aligned to best practice frameworks and applicable laws and regulations, as well as our contractual obligations. These enterprise-wide programs are designed to secure our facilities, information systems and safeguard data throughout its lifecycle, including data provided to third parties performing services on our behalf. Our cybersecurity program incorporates standards, processes, and activities over a number of domains, including governance, access controls, facility and data protection, IT systems and data transmission security, threat intelligence and incident response, third-party risk management, disaster recovery and vulnerability management.

Our cybersecurity risk management program monitors our systems and networks for threats, breaches, intrusions and other vulnerabilities; assesses the security of our company-wide software, applications and systems; conducts security audits and threat assessments; responds to cybersecurity incidents; and facilitates training for our employees. Our program includes procedures to identify cybersecurity risks and threats of our suppliers and third-party outsourcing providers with whom we interface, or who store, process, host or transmit confidential patient and employee data or other confidential information. Our Strategic Threat and Intelligence Center manages our threat landscape and uses a variety of security technology and threat intelligence tools designed to detect, prevent, block, analyze, and respond to cybersecurity threats. We collaborate with government agencies regarding potential cybersecurity threats and work with consultants and other third-party advisors to conduct security assessments and independent audits of the security and resilience of our systems and networks. At least annually, we review and test our program to simulate emergent threats and scenarios that could arise from potential cybersecurity attacks and data breaches. Our cybersecurity program is based on multiple security frameworks, including the National Institute of Standards and Technology’s NIST 800 Special Publication Information Security standard, MITRE ATT&CK Framework, the Payment Card Industry Data Security Standard, the System and Organization Controls for Service Organizations 2 (SOC 2), and ISO 9001:2015 and ISO 15189.

We have integrated cybersecurity risk management into our overall risk management infrastructure through our enterprise risk management program. The enterprise risk management program, which is driven by our executive leadership, entails a formal process that identifies, assesses, mitigates and manages the risks from both internal and external conditions that could significantly impact the Company and influence our business strategy and performance.

Although no cybersecurity incident during the year ended December 31, 2025 resulted in an interruption of our operations, known losses of critical data or otherwise had a material impact on our strategy, financial condition or results of operations, the scope of any future incident cannot be predicted. See “Item 1A. Risk Factors” for more information.

Governance

The Company’s Chief Information Security Officer (CISO), in coordination with the Company’s Chief Litigation Officer, Executive Director, Privacy Officer, Corporate Controller/Chief Accounting Officer, Executive Director, Corporate Security and other internal stakeholders, is responsible for leading the team responsible for assessing, identifying and managing cybersecurity and data privacy risks, including implementation of our cybersecurity risk management program. The CISO has extensive experience working in the IT and services industry and is a subject matter expert in varied topics including cybersecurity, data integrity, IT risk, enterprise architecture, third-party risk, threat intelligence, incident response, and

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regulatory compliance. Management committees consisting of senior officers of the Company regularly receive briefings on cybersecurity matters, who in turn regularly report to the Board of Directors and its committees on such matters.

The Board of Directors and its committees play an active role in overseeing our key enterprise level risks. Our Board, which annually reviews our enterprise risk management program, has delegated primary responsibility for overseeing the enterprise risk management program to the Audit and Finance Committee. The Board has delegated primary oversight of cybersecurity, a key enterprise risk, to the Cybersecurity Committee. The Board’s Quality and Compliance Committee oversees and receives regular updates on data privacy, another key enterprise risk.

The Audit and Finance Committee is responsible for reviewing our policies with respect to risk assessment and risk management, as well as our insurance programs, including regarding cybersecurity. Our internal audit team reports to the Audit and Finance Committee on summaries of findings from completed internal audits of, among other matters, our IT security systems and processes, including network security and data protection. The Audit and Finance Committee regularly reports to the Board on its activities.

The Cybersecurity Committee is responsible for the general oversight of our cybersecurity policies, plans, program and practices and risks related to cybersecurity and data security. The Cybersecurity Committee reviews the adequacy and effectiveness of our cybersecurity program and regularly receives reports from management on cybersecurity matters. It also reviews our management of risks and compliance with legal and regulatory requirements and industry standards related to our IT security systems and processes, including network security and data protection. The Cybersecurity Committee regularly reports on its activities to the Board to promote effective coordination and to ensure the entire Board remains apprised of the effectiveness of our cybersecurity risk management and our cybersecurity risk landscape, and also assesses how management is managing these risks.

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Our executive offices are located at 500 Plaza Drive, Secaucus, New Jersey. We maintain clinical testing laboratories throughout the continental United States; in several instances a joint venture of which we are a partner maintains the laboratory. We also maintain offices, data centers, call centers, distribution centers and patient service centers at locations throughout the United States. In addition, we maintain offices, patient service centers and clinical laboratories in locations outside the United States, including in Canada, Finland, Puerto Rico and Mexico. Our properties that are not owned are leased on terms and for durations that are reflective of commercial standards in the communities where these properties are located. We believe that, in general, our facilities are suitable and adequate for our current and anticipated future levels of operation and are adequately maintained. We believe that if we were unable to renew a lease on any of our facilities, we could find alternative space at competitive market rates and relocate our operations to such new location without material disruption to our business. Several of our principal facilities are highlighted below.

See Note 18 to the Consolidated Financial Statements (Part II, Item 8 of this Report) for information regarding legal proceedings in which we are involved.

Not applicable.

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PART II

Our common stock is listed and traded on the New York Stock Exchange under the symbol “DGX.” As of February 2, 2026, we had approximately 1,881 record holders of our common stock; we believe that the number of beneficial holders of our common stock exceeds the number of record holders.

The table below sets forth the information with respect to purchases made by or on behalf of the Company of its common stock during the fourth quarter of 2025.

(A)As of December 31, 2025, $0.4 billion remained available under our share repurchase authorization. In February 2026, our Board of Directors increased the size of our share repurchase program by $1 billion to $1.4 billion. The share repurchase authorization has no set expiration or termination date. Since the share repurchase program's inception in May 2003, our Board of Directors has authorized $14 billion of share repurchases of our common stock.

(B)Includes: (1) shares delivered or attested to in satisfaction of the exercise price and/or tax withholding obligations by holders of stock options (granted under the Company's Amended and Restated Employee Long-Term Incentive Plan) who exercised options; and (2) shares withheld (under the terms of grants under the Amended and Restated Employee Long-Term Incentive Plan) to offset tax withholding obligations that occur upon the delivery of outstanding common shares underlying restricted share units and performance share units.

(C)Excludes excise taxes on share repurchases of $2 million in aggregate, which will be paid in 2026.

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Performance Graph

Set forth below is a line graph comparing the cumulative total shareholder return on Quest Diagnostics' common stock since December 31, 2020 based on the market price of the Company's common stock and assuming reinvestment of dividends, with the cumulative total shareholder return of companies on the Standard & Poor's (S&P) 500 Stock Index and the S&P 500 Health Care (Sector) Index.

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See Management's Discussion and Analysis of Financial Condition and Results of Operations.

See Item 15(a)1 and Item 15(a)2.

None.

Conclusion Regarding Effectiveness of Disclosure Controls and Procedures

Under the supervision and with the participation of our management, including our Chief Executive Officer and our Chief Financial Officer, we have evaluated the effectiveness of our disclosure controls and procedures (as defined under Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934, as amended). Based upon that evaluation, our Chief Executive Officer and our Chief Financial Officer concluded that our disclosure controls and procedures were effective as of the end of the period covered by this annual report.

Report of Management on Internal Control Over Financial Reporting

Changes in Internal Control

During the fourth quarter of 2025, there were no changes in our internal control over financial reporting (as defined in Rule 13a-15(f) under the Securities Exchange Act of 1934, as amended) that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

(b) Rule 10b5-1 and Non-Rule 10b5-1 Trading Arrangements by Our Directors and Officers

Our directors and officers (as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934, as amended) adopted, terminated or modified the Rule 10b5-1 trading arrangements (as defined in Item 408 of Regulation S-K) set forth in the table below. No non-Rule 10b5-1 trading arrangements were adopted, modified or terminated by any director or officer during the period covered by this report.

• Includes shares of common stock to be released from (a) stock options and/or restricted stock units that are expected to vest and/or (b) performance share awards that may vest, subject to the satisfaction of the applicable performance metrics. The actual number of shares of common stock that will be released is not yet determinable and the actual number of shares of common stock that will be sold will be net of the number of shares withheld to satisfy employee tax withholding obligations.

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Not applicable.

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PART III

Our Code of Ethics applies to all employees, executive officers and directors, including our Chief Executive Officer, Chief Financial Officer and Corporate Controller. You can find our Code of Ethics on our corporate governance website, www.QuestDiagnostics.com/investor. We will post any amendments to the Code of Ethics, and any waivers that are required to be disclosed by the rules of either the SEC or the New York Stock Exchange, on our website.

Information regarding the Company's executive officers is contained in Part I, Item 1 of this Report under “Information about our Executive Officers.” Information regarding the directors and executive officers of the Company appearing in our Proxy Statement to be filed by April 30, 2026 (“Proxy Statement”) under the captions “Proposal No. 1 - Election of Directors,” “Director Independence,” “Board Committees” and "Delinquent Section 16(a) Reports" is incorporated by reference herein.

We have an insider trading policy related to the purchase, sale and other transactions in our securities entered into by our directors, officers, employees and related other persons and by us. The insider trading policy is designed to comply and promote compliance with the securities laws and related rules and regulations, the New York Stock Exchange listing standards and our own Code of Ethics. Our insider trading policy is filed as Exhibit 19 to this Report.

Information appearing in our Proxy Statement under the captions “2025 Director Compensation Table,” “Compensation Discussion and Analysis,” “Information Regarding Executive Compensation” (excluding the information under the subheading "Pay Versus Performance") and “Compensation Committee Report” is incorporated by reference herein.

Information regarding security ownership of certain beneficial owners and management appearing in our Proxy Statement under the captions “Stock Ownership Information” and "Equity Compensation Plan Information" is incorporated by reference herein.

Information regarding certain relationships and related transactions appearing in our Proxy Statement under the captions “Related Person Transactions” and “Director Independence” is incorporated by reference herein.

Information regarding principal accountant fees and services appearing in our Proxy Statement under the caption “Audit" (excluding the information under the subheading “Audit and Finance Committee Report”) is incorporated by reference herein.

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PART IV

(a)Documents filed as part of this Report.

1.Index to financial statements and supplementary data filed as part of this Report.

2. Financial Statement Schedules

None.

3. Exhibits

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(b)Exhibits filed as part of this Report.

The exhibit index in (a) above is incorporated herein by reference.

(c)None.

None.

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Signatures

Pursuant to the requirements of Sections 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, on February 26, 2026.

Each individual whose signature appears below constitutes and appoints Michael E. Prevoznik and Sean D. Mersten, and each of them singly, his or her true and lawful attorneys-in-fact and agents with full power of substitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K filed with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all the said attorneys-in-fact and agents or any of them or their or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacities indicated on February 26, 2026.

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QUEST DIAGNOSTICS INCORPORATED AND SUBSIDIARIES

MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Our Company

Diagnostic Information Services

Quest Diagnostics works across the healthcare ecosystem to create a healthier world, one life at a time. Our diagnostic information services ("DIS") business provides diagnostic insights from the results of our laboratory testing to empower people, physicians, and organizations to take action to improve health outcomes. Derived from one of the world's largest databases of de-identifiable clinical lab results, our diagnostic insights reveal new avenues to identify and treat disease, inspire healthy behaviors and improve healthcare management. In the right hands and with the right context, our diagnostic insights can inspire actions that transform lives and create a healthier world. We provide services to a broad range of customers within our primary customer channels - physicians (including those associated with accountable care organizations ("ACOs") and Federally Qualified Health Centers ("FQHCs")), hospitals, and patients and consumers. Our other customers include health plans, employers, new and emerging retail healthcare providers, government agencies, pharmaceutical companies and other commercial clinical laboratories. We offer broad access to clinical testing through a network of laboratories, patient service centers, phlebotomists in physician offices, and our connectivity resources, including call centers and mobile phlebotomists, nurses and other health and wellness professionals. Our large in-house staff of medical and scientific experts, including medical directors, scientific directors, genetic counselors and board-certified geneticists, provide medical and scientific consultation to healthcare providers and patients regarding our tests and test results, and help them best utilize our services to improve outcomes and enhance satisfaction. During 2025, we processed approximately 244 million test requisitions through our extensive laboratory network.

Clinical testing is an essential element in the delivery of healthcare services. Clinical testing is used for predisposition, screening, monitoring, diagnosis, prognosis and treatment choices of diseases and other medical conditions. We primarily compete with three types of clinical testing providers: commercial clinical laboratories, hospital-affiliated laboratories and physician-office laboratories. In addition, we compete with many smaller regional and local commercial clinical laboratories, specialized advanced laboratories and providers of consumer-initiated testing.

The clinical testing industry is subject to seasonal fluctuations in operating results and cash flows. Typically, testing volume declines during vacation and major holiday periods, reducing net revenues and operating cash flows below annual averages. Testing volume is also subject to declines due to severe weather or other events (such as public health emergencies and health pandemics), which can deter patients from having testing performed and which can vary in duration and severity from year to year. Additionally, orders for clinical testing generated from customers, including physicians, hospitals, and consumers, can be affected by factors such as changes in the economy and regulatory environment, which affect the number of unemployed and uninsured, and design changes in healthcare plans, which affect utilization as well as patient responsibility for healthcare costs.

We assess our revenue performance for our DIS business based upon, among other factors, volume (measured by test requisitions) and revenue per requisition. Each test requisition accompanies patient specimens, indicating the test(s) to be performed and the party to be billed for the test(s). Revenue per requisition is impacted by various factors, including, among other items, the impact of fee schedule changes (i.e., unit price), test mix, payer mix, business mix, and the number of tests per requisition. Management uses number of requisitions and revenue per requisition data to assist with assessing the growth and performance of the business, including understanding trends affecting number of requi

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