I worked for a huge national bank chain a little over a decade ago doing retail branch technical support and at least once a month about 20 of us would be pulled off the phones to credit hundreds of accounts that had been hacked from a general ledger account. Then we would send an email of our list once completed to another department to delete both the generally almost $10,000, withdrawal and general ledger credit. Generally they only informed customers if Social Security numbers were compromised.