After the financial crisis, several of the largest banks in the U.S., such as Bank of America (BAC 0.59%) and Wells Fargo (WFC 0.87%), have seen their deposit levels soar to all-time highs. In the current climate of low interest rates, net interest margins have been squeezed tight for many big banks, and while stockpiling deposits like this may mean reduced revenue in the short run, in this video, Fool financials analysts David Hanson and Matt Koppenheffer tell investors that these huge stockpiles may set these banks up to take full advantage of higher interest rates -- when they inevitably rise again.