Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why have U.S. bank interest rates been so low for the past few years?
These rates are so low because the cost of money is so low. Specifically, two rates are near zero.  The Federal Reserve discount rate, which is "the interest rate charged to commercial banks and other depository institutions on loans they receive from their regional Federal Reserve Bank's lending facility--the discount window." The effective federal funds rate, which is the rate banks pay when they trade balances with each other through the Federal Reserve. Banks want to profit on the loans they make, like mortgage loans. To do so, they try to maximize the difference between the rates they charge on mortgages and other loans (revenue), and the rates they pay savings account holders, the Federal Reserve or other banks to obtain funds (expenses). This means that the rates they offer to pay are as close to these rates as possible. As the charts shows, both rates have been cut significantly since the start of the recession, either through open market operations (the federal funds rate) or directly (the discount rate). The discount rate is set directly by the regional Federal Reserve banks every 14 days.   In most cases, the federal funds rate is lower than the discount rate, in order to encourage banks to lend money to each other instead of borrowing it from the Fed. In the past, however, there have been rare instances where the federal funds rate has exceeded the discount rate, and it's been cheaper for banks to borrow money directly from the Fed than from each other.