Quest Diagnostics reports possible patient-records breach

Quest Diagnostics discovered unauthorized access to its Quanum Lab Services Manager on October 21, 2026, and disclosed it the next day in an SEC 8-K under Item 8.01. The company said an unauthorized party accessed the system certain clients use to order tests and view results, and that it believes certain patient records were accessed. Quest said it immediately activated its cybersecurity incident response procedures to contain the breach, evaluate the nature and scope of the incident, and implement corrective actions. It notified federal law enforcement and engaged external cybersecurity experts. It said the breach has not materially disrupted the Company's business operations or its ability to serve patients. The number of patients and which records remain undetermined. The filing landed the same day Quest posted third-quarter 2026 revenue of $3.1 billion, up 10% year over year. Jim Davis, chairman, CEO and president, said the company was raising our revenue and EPS guidance for the full year. Sean D. Mersten, VP and corporate secretary, signed the filing for the firm headquartered at 500 Plaza Drive, Secaucus, NJ 07094. Prior breaches affected about 34,000 people in 2016 and about 11.9 million patients in 2019 via American Medical Collection Agency. Quest confirmed the incident was unrelated to recently reported PHP vulnerabilities. CONTESTED: none found. Scope of affected records remains unresolved.