Interesting article about the role of Excel in the London Whale scandal:
From http://baselinescenario.com/2013/02/09/the-importance-of-excel/To summarize: JPMorgan’s Chief Investment Office needed a new value-at-risk (VaR) model for the synthetic credit portfolio (the one that blew up) and assigned a quantitative whiz (“a London-based quantitative expert, mathematician and model developer” who previously worked at a company that built analytical models) to create it. The new model “operated through a series of Excel spreadsheets, which had to be completed manually, by a process of copying and pasting data from one spreadsheet to another.”
There is a post I remember reading a while back (unfortunately I can't seem to find it anymore) that pointed out that one of the great strengths of Excel was that, as opposed to usual programming languages, in Excel the data is shown and the functions are hidden. This means that an user tinkering with some functions will immediately see the results of what he's doing, whereas in other programming languages she will have to pass data to her program to see what it does. As the article says:
While all software breaks occasionally, Excel spreadsheets break all the time. But they don’t tell you when they break: they just give you the wrong number.
This has the effect of empowering less advanced users, while at the same time making it way too easy to end up with corrupted data, as explained in the article.