Quest Diagnostics reports unauthorized access to Quanum LSM system; some patient records accessed

QUEST DIAGNOSTICS INC

• On October 21, 2026, Quest learned of unauthorized access to its Quanum LSM system, which clients use to place test orders and receive and look up results.
• Company believes an unauthorized party accessed certain patient records; the full scope of the access remains under investigation.
• Quest notified federal law enforcement and engaged external cybersecurity experts; incident response procedures were initiated to contain the activity.
• The incident has not materially disrupted business operations or the company's ability to serve patients, according to the filing.