HSBC has admitted losing a server containing data on 159,000 customers.
The server went missing on 26 April from its Kwun Tong district branch in Hong Kong during renovation work on 26 April. The server held customer names, account numbers, transaction amounts and transaction types, the banking giant confirmed.
HSBC said the server is protected by "multiple layers of security" and the risk of data breaches and fraud is "deemed to be low".
It also said the server contained no PIN codes or online banking login credentials.
The bank said it has reported the incident to the police, the Hong Kong Monetary Authority, and the Hong Kong privacy commissioner.
The Hong Kong incident is the latest security foul-up involving HSBC. In April, HSBC admitted it lost an unencrypted disc containing 370,000 customer details in the post.
HSBC has also struggled with its Secure e-payments system, with three outages reported this year that left merchants stranded and unable to process payments.