is that a sacked employee of the bank was able to get his revenge-seeking hands on this quantity of confidential data without anyone knowing about it.
Regardless of what you think about the way the Swiss banking laws have been used to conceal activities, the customers (not all of whom have been "fiddling whilst Rome burns") should expect their bank to provide them with a degree of confidentiality and privacy.
I always imagined that Swiss banks were pretty secure, and that it was extremely difficult for a disgruntled employee to get hold of peoples' personal data in this way. Apparently I was wrong. I doubt it will do the bank in question a lot of good in terms of publicity.