Hackers breached some HSBC customers' accounts in the United States in October and accessed their information, the bank said in a regulatory filing on Tuesday.
It was not immediately clear how many accounts were breached or whether any money was stolen.
"HSBC regrets this incident, and we take our responsibility for protecting our customers very seriously." an HSBC spokeswoman said.
"We have notified customers whose accounts may have experienced unauthorized access and offered them one year of credit monitoring and identify theft protection service.”
(Reporting by Lawrence White; Editing by David Goodman)