DGX: Leadership change

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On October 6, 2026, Quest Diagnostics Incorporated (the “Company”) announced that Catherine T. Doherty will retire in July 2027. Until then, effective November 1, 2026, Ms. Doherty will transition to a new role as Executive Vice President with responsibilities including health systems, the Company’s joint venture with Corewell Health, and Project Nova, the Company’s multi-year project to modernize its “Order to Cash” business processes, which includes the related information technology infrastructure and underlying enabling technologies. In connection with this transition, the Company’s Compensation and Leadership Development Committee (the “Committee”) approved no change to Ms. Doherty’s annual base salary of $650,000 or annual incentive compensation under the Company's Senior Management Incentive Plan with a target amount of 80% of base salary. The Committee also approved an equity award under the Company’s Employee Long-Term Incentive Plan (“Employee Plan”) with a grant date of November 3, 2026 and a target value of $1,200,000, allocated 100% to restricted stock units. This award will be subject to terms and conditions that are substantially the same as the annual long-term incentive awards granted under the Employee Plan in 2026 to other Company senior executives. Signature Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized. October 6, 2026 QUEST DIAGNOSTICS INCORPORATED By: /s/ Sean D. Mersten Sean D. Mersten Vice President and Corporate Secretary