Cyber incident hits McKesson (NYSE: MCK) systems; impact under review Rhea-AI Filing Summary McKesson Corporation (MCK) reported that on August 25, 2026 it discovered a cybersecurity incident affecting its information systems. The investigation is in its early stages, and additional information and updates are being made available on the company’s website at www.mckesson.com/cybersecurity. As of this report, McKesson states it has not determined that the incident is material or that it has had, or is reasonably likely to have, any material impact on the company, including its financial condition or results of operations. Positive - None. Negative - None. 8-K Event Classification 2 items: 7.01, 9.01 2 items Item 7.01 Regulation FD Disclosure Disclosure Material non-public information disclosed under Regulation Fair Disclosure, often investor presentations or guidance. Item 9.01 Financial Statements and Exhibits Exhibits Financial statements, pro forma financial information, or exhibit attachments filed with this report. Key Figures Cybersecurity incident discovery date: August 25, 2026 1.625% Notes due 2026: 1.625% 3.125% Notes due 2029: 3.125% +1 more 4 metrics Cybersecurity incident discovery date August 25, 2026 Date McKesson discovered the cybersecurity incident affecting its information systems 1.625% Notes due 2026 1.625% Interest rate on McKesson’s notes due 2026 listed on the New York Stock Exchange 3.125% Notes due 2029 3.125% Interest rate on McKesson’s notes due 2029 listed on the New York Stock Exchange Report signature date August 28, 2026 Date McKesson’s 8-K report was signed by the Executive Vice President and Chief Legal Officer Key Terms cybersecurity incident, emerging growth company, Inline XBRL 3 terms cybersecurity incident technical "McKesson Corporation discovered a cybersecurity incident affecting its information systems." A cybersecurity incident is an event where someone's computer systems or data are attacked or broken into without permission. It matters because it can lead to stolen information, financial loss,