U.S. wireless carrier T-Mobile said on Thursday it was investigating a data breach that potentially affected 37 million accounts.
The company said it identified malicious activity on Jan. 5 and contained it within a day, adding that no sensitive data such as financial information was compromised.
However, some basic customer information was obtained, such as name, billing address, email and phone number, T-Mobile said.
"Our investigation is still ongoing, but the malicious activity appears to be fully contained at this time, and there is currently no evidence that the bad actor was able to breach or compromise our systems or our network," the company said, adding it had begun notifying impacted customers.
Shares in the company fell 2% in after-hours trade.
