T-Mobile ($TMUS@US) revealed in an SEC filing that it had been exposed to a hack going back to November 25th. The hacker accessed the name, billing addresses, emails, phone numbers, and birth dates of 37 million customers. The mobile communications carrier said that it detected the breach on January 5th and made repairs within a day. The company said the hacker didn’t breach a company system but abused an application programming interface or API. This was T-Mobile’s eighth hack since 2018.