Software Testing Blog

In this month’s installment of This Week In Testing, the date was May 1996 and the setting was the First National Bank of Chicago (insert dramatic pause here). The gist? Software “glitches” caused the bank accounts of 823 customers of the major US bank to be credited with a total of $924,844,208.32 each.

According to The American Bankers Association, all of $763.9 billion — more than six times the total assets of First Chicago NBD Corp. — was the largest error in US banking history.

And the reason given? Inadequate testing of course! The bank updated its ATM transaction software with new message codes. The message codes were unfortunately not tested on all ATM protocols, which resulted in some ATMs interpreting the codes as huge increases to customer balances.

This isn’t the first time we bring up banking bugs. You might remember Software Bugs: You Win Sum, You Lose Sum, the post about a man in Orlando who while making a routine bank transfer was shocked to see his balance at $88,888,888,888.88.

What other bugs have you recently heard or read about with such huge financial implications? Any mobile banking bugs?