In a move that stunned marketwatchers and brought some much needed holiday cheer to consumers, the Federal Reserve Board lowered by a quarter percentage point the federal funds rate, the interest that banks charge one another on overnight loans, from 5.75 percent to 5.5 percent. The key rate effects borrowing costs for consumers. The cut was announced after the highly anticipated meeting of the central bank's Federal Open Market Committee today. Federal Reserve Chairman Alan Greenspan noted that a main reason for the reduction is that inflationary pressures are easing. This was the Fed's second interest rate cut this year, after seven interest-rate increases over a one-year period.