Proactive Investors - The personal data of 73 million former and current AT&T Inc (NYSE:T, ETR:SOBA) customers has been published online, the telecommunications giant confirmed over the weekend.
The company said that the information - which varied by account but may have included full name, email address, mailing address, social security number, and date of birth, among other data - was published on the dark web approximately two weeks ago.
It has launched an investigation into the matter with the support of internal and external cybersecurity experts and said that the source of the data is still being assessed, with it not yet determined if the data originated from AT&T or one of its vendors.
The data appears to be from 2019 or earlier and does not appear to contain personal financial information or call history, the company said.
It relates to 7.6 million current AT&T customers and 65.4 former account holders.
AT&T said it was reaching out to affected customers by email or letter and had reset their passcodes. It encouraged customers to monitor their account activity and credit reports.
Shares of AT&T traded 1.3% lower at $17.38 at noon on Monday.