Good question. Idiots at Chase spent $2 billion buying worthless securities. The people who sold them got the $2 billion. Most of the sellers were probably other banks, they're all full of crooks and stupid people who figure, it's not their money, it's ours, so who cares if they lose it?
There are financial misfortunes that cause a given amount like $2 billion to get lost in financial institutions like banks. Some of them include cash embezzlement by unethical employees, theft and unavoidable catastrophes like fire.