....Do you not understand that a bank is a creature of "we'll keep it safe until you need it?" That a bank, even if the ultimate investment of float they did,

....Do you not understand that a bank is a creature of "we'll keep it safe until you need it?" That a bank, even if the ultimate investment of float they did, finds themselvesbin a position they cannot reconstitute sufficient float to pay out it's liabilities has ultimately engaged in bad/risky investments? Risk can happen in terms of "Wow those turned out to be really crappy mortgages," ot in "Well, I just dumped all that money in single year TBills, and the interest rate went up!" Any bond in an increasing interest rate environment in the abscence of enough time being available to fully mature is setting principle on fire. Because you can't cash out, because no one will buy. That's what went sour. You bet peoples money on things'll stay the same... And you were wrong, and there was no time to paper over it with the coupons of those bills.