In 2012 JPMorgan Chase lost a bunch of money; it’s difficult to get a hard figure, but the agreement seems to be that it was around $6 billion. As is often the case in modern finance, there are a lot of complicated aspects to how the trading was done and structured (none of which I claim to understand). But the chain of mistakes featured some serious spreadsheet abuse, including the calculation of how big the risk was and how losses were being tracked.
