In a case of too stupid not to share Commonwealth Bank lost 12 million customers’ data including their financial histories from 2004 to 2014 but this wasn’t your normal breach. The magnetic tape backups just went missing. They hired a company to destroy the backups and no one has any idea what happened after they left the storage facility. They hired KPMG to help track them down after police were unable to find anything who, after a lengthy search, concluded that the tapes were most likely destroyed. This just highlights the fact that physical security and chain of custody is really important.
https://gizmodo.com/major-bank-loses-12-million-customers-data-in-the-most-1825711247