The latest "Minutes of the Federal Open Market Committee" tells us, "The staff noted that banks' liquidity management practices had changed markedly since the financial crisis, with large banks now maintaining substantial buffers of reserves, among other high-quality liquid assets, to meet potential outflows and to comply with regulatory requirements. Information from bank contacts as well as a survey of banks indicated that, in an environment in which money market interest rates were very close to the interest rate paid on excess reserve balances, banks would likely be comfortable operating with much lower levels of reserve balances than at present but would wish to maintain substantially higher levels of balances than before the crisis. On average, survey responses suggested that banks might reduce their reserve holdings only modestly from those 'lowest comfortable' levels if money market interest rates were somewhat above the interest on excess reserves (IOER) rate. Across banks, however, individual survey responses on this issue varied substantially." It adds, "The staff highlighted how changes in the determinants of reserve demand since the crisis could affect the tradeoffs between two types of operating regimes: (1) one in which aggregate excess reserves are sufficiently limited that money market interest rates are sensitive to small changes in the supply of reserves and (2) one in which aggregate excess reserves are sufficiently abundant that money market interest rates are not sensitive to small changes in reserve supply. In the former type of regime, the Federal Reserve actively adjusts reserve supply in order to keep its policy rate close to target. This technique worked well before the financial crisis, when reserve demand was fairly stable in the aggregate and largely influenced by payment needs and reserve requirements. However, with the increased use of reserves for precautionary liquidity purposes following the crisis, there was some uncertainty about whether banks' demand for reserves would now be sufficiently predictable for the Federal Reserve to be able to precisely target an interest rate in this way. In the latter type of regime, money market interest rates are not sensitive to small fluctuations in the demand for and supply of reserves, and the stance of monetary policy is instead transmitted from the Federal Reserve's administered rates to market rates -- an approach that has been effective in controlling short-term interest rates in the United States since the financial crisis, as well as in other countries where central banks have used this approach."