Notice of Data Event

We are posting this notice to provide important information regarding a recent security incident previously disclosed in June 2026 that impacted personal information maintained by iRhythm, including Protected Health Information (PHI) as defined by the Health Insurance Portability and Accountability Act (HIPAA). We want to provide individuals served by iRhythm with details about the incident and explain that we continue to take significant measures to protect their information.

On or around June 8, 2026, iRhythm detected unauthorized access in certain third-party-hosted business applications. Upon detecting the unauthorized access, we promptly implemented our incident response plan. As part of our investigation, we have been working very closely with external cybersecurity professionals experienced in handling these types of incidents. After completing our forensic investigation, we learned certain data we store was accessed and downloaded by unauthorized individuals between June 3 and June 8, 2026.  

Following the forensic investigation, we carried out a review to determine the nature of the impacted data. This review concluded the impacted data includes: patient name; patient contact information, including address, email address, and phone number; iRhythm patient account number; iRhythm device serial number; patient insurance number; date of service; and date of birth.

iRhythm has no evidence that any personal information has been or will be used to commit identity theft. However, commencing on October 2, 2026, iRhythm notified impacted individuals for whom we have contact information. Notified individuals have been provided with instructions on best practices to protect their information, which are found below. 

Out of an abundance of caution, those served by iRhythm are encouraged to take steps to protect themselves. This includes protecting themselves against medical identity theft and identity fraud, placing a fraud alert/security freeze on their credit files, obtaining free credit reports, and remaining vigilant in reviewing financial account statements and credit reports for fraudulent or irregular activity on a regular basis. 

iRhythm is committed to maintaining the privacy and security of personal information in our possession and we have taken precautions to safeguard it. We regularly evaluate and modify our practices and internal controls to safeguard the security and privacy of the information we maintain, and we have taken steps to mitigate the risk to persons impacted by this incident.

If you have any questions regarding this incident, please call our dedicated toll-free response line at 1-844-770-7175. This response line is staffed with professionals familiar with this incident and knowledgeable on what you can do to protect against misuse of your information. The response line is available 8:00am to 8:00pm ET, Monday through Friday, excluding holidays.

As iRhythm previously reported, we have not identified any impact to our products, our clinical or medical device systems, our connections to customers, our manufacturing and distribution operations, patient safety, or our ability to meet patient needs. In addition, iRhythm does not store or retain individual financial account information or payment card information. iRhythm continues to believe, as previously stated in the Current Report on Form 8-K dated June 15, 2026, that the incident is not reasonably likely to have a material impact on the Company’s financial condition or results of operations.

The privacy and security of the personal information we maintain is of the utmost importance to us, and we sincerely regret any inconvenience this incident may cause.

Sincerely,

iRhythm 

Steps Individuals Can Take to Protect Personal Information

1. Protecting Your Medical Information.

We have no evidence that your medical information involved in this incident was or will be used for any unintended purposes. However, the following practices can provide additional safeguards to protect against medical identity theft:

• Only share your health insurance cards with your health care providers and other family members who are covered under your insurance plan or who help you with your medical care. 

• Review your “explanation of benefits statement” which you receive from your health insurance company. Follow up with your insurance company or care provider for any items you do not recognize. If necessary, contact the care provider on the explanation of benefits statement and ask for copies of medical records from the date of the potential access (noted above) to current date.

• Ask your insurance company for a current year-to-date report of all services paid for you as a beneficiary. Follow up with your insurance company or the care provider for any items you do not recognize. 

2. Placing a Fraud Alert on Your Credit File.

We recommend that you place an initial one-year “fraud alert” on your credit files, at no charge. A fraud alert tells creditors to contact you personally before they open any new accounts. To place a fraud alert, call any one of the three major credit bureaus at the numbers listed below. As soon as one credit bureau confirms your fraud alert, they will notify the others. 

3. Placing a Security Freeze on Your Credit File.

Additionally, you may request a “security freeze” be placed on your credit file, at no charge. A security freeze prohibits, with certain specific exceptions, the consumer reporting agencies from releasing your credit report or any information from it without your express authorization. However, please be aware that placing a security freeze on your credit report may delay, interfere with, or prevent the timely approval of any requests you make for new loans, credit, mortgages, employment, housing, or other services. There might be additional information required, and as such, to find out more information, please contact the three nationwide credit reporting agencies (contact information provided below). You may place a security freeze on your credit report by contacting all three nationwide credit reporting companies at the numbers below and following the stated directions or by sending a request in writing, by mail, to all three credit reporting companies:

In order to place the security freeze, you will need to supply your name, address, date of birth, Social Security number and other personal information. After receiving your freeze request, each credit reporting company will send you a confirmation letter containing a unique PIN (personal identification number) or password. Keep the PIN or password in a safe place. You will need it if you choose to lift the freeze. 

4. Obtaining a Free Credit Report.

Under federal law, you are entitled to one free credit report every 12 months from each of the above three major nationwide credit reporting companies. Call 1-877-322-8228 or request your free credit reports online at www.annualcreditreport.com. Once you receive your credit reports, review them for discrepancies. Identify any accounts you did not open or inquiries from creditors that you did not authorize. Verify all information is correct. If you have questions or notice incorrect information, contact the credit reporting company.

5. Additional Helpful Resources.

Even if you do not find any suspicious activity on your initial credit reports, the Federal Trade Commission (FTC) recommends that you check your credit reports periodically. If you find suspicious activity on your credit reports or have reason to believe your information is being misused, call your local law enforcement agency and file a police report. Be sure to obtain a copy of the police report, as many creditors will want the information it contains to absolve you of the fraudulent debts. You may also file a complaint with the FTC by contacting them on the web at www.ftc.gov/idtheft, by phone at 1-877-IDTHEFT (1-877-438-4338), or by mail at Federal Trade Commission, Consumer Response Center, 600 Pennsylvania Avenue, NW, Washington, DC 20580. Your complaint will be added to the FTC’s Identity Theft Data Clearinghouse, where it will be accessible to law enforcement for their investigations. In addition, you may obtain information from the FTC about fraud alerts and security freezes.

Connecticut Residents: You may contact and obtain information from Connecticut Attorney General’s Office, 165 Capitol Ave, Hartford, CT 06106, 1-860-808-5318, www.ct.gov/ag.

Iowa Residents: You may contact law enforcement or the Iowa Attorney General’s Office to report suspected incidents of identity Theft: Office of the Attorney General of Iowa, Consumer Protection Division, Hoover State Office Building, 1305 East Walnut Street, Des Moines, IA 50319, www.iowaattorneygeneral.gov, Telephone: 515-281-5164.

Maryland Residents: You may obtain information about avoiding identity theft from the Maryland Attorney General’s Office: Office of the Attorney General of Maryland, Consumer Protection Division, 200 St. Paul Place, Baltimore, MD 21202, https://www.marylandattorneygeneral.gov/, Telephone: 888-743-0023.

Massachusetts Residents: Under Massachusetts law, you have the right to obtain a police report in regard to this incident. If you are the victim of identity theft, you also have the right to file a police report and obtain a copy of it.

New Mexico Residents: You have rights under the federal Fair Credit Reporting Act (FCRA). These include, among others, the right to know what is in your file; to dispute incomplete or inaccurate information; and to have consumer reporting agencies correct or delete inaccurate, incomplete, or unverifiable information. For more information about the FCRA, please visit https://www.ftc.gov/system/files/ftc_gov/pdf/fcra-may2023-508.pdf or www.ftc.gov. In addition, New Mexico consumers have the right to obtain a security freeze (as explained above) or submit a declaration of removal to remove information placed in your credit report as a result of being a victim of identity theft.

New York Residents: You may obtain information about preventing identity theft from the New York Attorney General’s Office: Office of the Attorney General, The Capitol, Albany, NY 12224-0341; https://ag.ny.gov/consumer-frauds-bureau/identity-theft; Telephone: 800-771-7755.

North Carolina Residents: You may obtain information about preventing identity theft from the North Carolina Attorney General’s Office: Office of the Attorney General of North Carolina, Consumer Protection Division, 9001 Mail Service Center, Raleigh, NC 27699-9001, www.ncdoj.gov/, Telephone: 877-566-7226 (Toll-free within North Carolina), 919-716-6000

Oregon Residents: You may obtain information about preventing identity theft from the Oregon Attorney General’s Office: Oregon Department of Justice, 1162 Court Street NE, Salem, OR 97301-4096, www.doj.state.or.us/, Telephone: 877-877-9392.

Rhode Island Residents: You may contact law enforcement, such as the Rhode Island Attorney General’s Office, to report incidents of identity theft or to learn about steps you can take to protect yourself from identity theft. You can contact the Rhode Island Attorney General at: Rhode Island Office of the Attorney General, 150 South Main Street, Providence, RI 02903, www.riag.ri.gov, 401-274-4400.

Washington D.C. Residents: You may obtain information about preventing identity theft from the Office of the Attorney General for the District of Columbia, 400 6th Street NW, Washington D.C. 20001, https://oag.dc.gov/consumer-protection, Telephone: 202-442-9828.

West Virginia Residents: You have the right to ask that nationwide customer reporting agencies place “fraud alerts” in your file to let potential creditors and others know that you may be a victim of identity theft, as described above. You also have a right to place a security freeze on your credit report, as described above.