The Federal Reserve changed how it pays banks interest in 2008, which affected how banks behave. By setting the interest rate on required and excess reserves above the federal funds rate, the Fed influenced bank lending and borrowing behavior. This new system made banks hold more excess reserves and rely less on interbank lending. It also made the interest rate on excess reserves more important for controlling bank credit compared to the federal funds rate. This change helped stabilize bank credit during shocks to deposit supply but made it more sensitive to changes in loan demand. The Fed could save money by setting different interest rates on required and excess reserves without hurting monetary policy effectiveness.