A major hacking incident disclosed over the weekend led to a minor sell-off in AT&T (T 1.61%) stock as the trading week kicked off on Monday. The telecom giant's shares dipped by 0.6% on the day, which was a steeper fall than the bellwether S&P 500 index's 0.2% slide.
Large data set found on the dark web
The previous Saturday, AT&T revealed that data fields specific to the company were found in a data set released on the dark web. This occurred roughly two weeks previously and, according to a preliminary analysis conducted by the telecom incumbent, comes from a data set from 2019 or earlier. The analysis found that roughly 7.6 million current AT&T account holders were affected, and about 65.4 million former users.
The company added that it is reaching out to the people affected by the hack, and it has reset their passcodes. Its analysis indicated that the compromised data contains no personal financial information or phone call history.
AT&T said it is investigating the situation with both internal and external cybersecurity experts. At this time, it is unknown whether the compromised data came from the company directly, or from a related third party.
Followed a widespread outage in February
AT&T is already under scrutiny by the public following a service outage in February that affected over 1.7 million users. Although it said this was due to a technical error, this plus the data breach wasn't exactly inspiring confidence in its safety and security measures on Monday.
