Franklin-based hospital company Community Health Systems Inc. had a data breach that affected an estimated 4.5 million patients.
In a statement filed with the Securities and Exchange Commission, CHS reported a hacker in China bypassed the company's security measures, likely in April and June of 2014.
CHS, which worked with cybersecurity company Mandiant to help address the threat, said that the data affected in the breach is non-medical, but does include sensitive information such as patient names, addresses, birthdates, telephone numbers and Social Security numbers.
CHS says it will notify all affected patients and provide them with protection services.
The security breach shouldn't affect the company's bottom line, the company said in its report:
"While this matter may result in remediation expenses, regulatory inquiries, litigation and other liabilities, at this time, the company does not believe this incident will have a material adverse effect on its business or financial results."
CHS is the largest hospital company in the country, in terms of the number of hospitals. Out of CHS' 206 hospitals, 19 are in Tennessee.