An Investigation by Buzzfeed News Australia has found the Commonwealth Bank lost copies of financial statements from 12 million customers in 2016.
The breach occurred when magnetic tape drives from a decommissioned data storage centre went missing during the period they were scheduled for transport to another site for destruction.
A forensic team hired by the Commonwealth Bank suggested that it was likely the tape drives either fell off the back of a truck en-route to their final destination or their destruction was simply not properly documented.
The breach was promptly reported to regulatory bodies, but the Commonwealth bank chose not to disclose it to the public after their investigation into the incident concluded the data had not been recovered by any malicious actors and that any recovery at a future date is unlikely.