Mizuho Bank May Have Lost Data on Thousands of Clients

The Yomiuri Shimbun

19:56 JST, February 26, 2026

Mizuho Bank, Ltd. announced on Thursday that storage media has been lost that may have contained information on tens of thousands of individuals and businesses who conducted transactions with the bank.

According to Mizuho, the information concerned 15,084 individuals and 43,054 corporations. Their transactions were conducted at 18 locations in 11 countries and regions overseas, including China and Australia. The breakdown of individuals was 5,483 customers and 9,601 bank employees. Names, addresses, account numbers and other details may have been leaked externally. According to the announcement, the media was lost by a contractor that was handling system development for overseas operations.

The information is said to have been processed to prevent its contents from being deciphered. Mizuho Bank also revealed last June that it mistakenly leaked the email addresses of 5,572 individual customers to a business partner.