Banks do not park such a big fraction of their funds in such a long term investment. They should have chosen a ladder of differently maturity timelines to trad

Banks do not park such a big fraction of their funds in such a long term investment. They should have chosen a ladder of differently maturity timelines to trade off between yield and availability. For example, they could have invested more in short term treasuries instead, which yield 4.5% now. In finance terms, they were not hedged against interest rate risk.