WASHINGTON, Oct. 31 (Xinhua) -- The U.S. Federal Reserve lowered a key interest rate by a quarter percentage point to 4.5 percent on Wednesday to help the economy ride the current housing slump and credit crunch.

This was the second consecutive cut in the central bank's target for the federal funds rate, the interest rate that commercial banks charge each other for overnight loans, in the last six weeks.

On Sept. 18, the Fed lowered the key rate by an aggressive half a percentage point to 4.75 percent from 5.25 percent, where it had stood since June 2006.

That was the Fed's first rate cut in more than four years, designed to ease tightening credit stemming from troubles in the high-risk subprime mortgage market, which offers loans to people with lower credit and income.

In June 2003, in an attempt to bring the long economic downturn to a halt, the Fed lowered the short-term interest rate to 1 percent, taking it to its lowest level since 1958.

From June 2004 the Fed began a succession of 17 consecutive interest rate increases, raising it from 1 percent to 5.25 percent. The latest interest-hike came on June 29, 2006, when the Fed boost the federal funds interest rate to 5.25 percent, the highest level in more than five years.

Since then, the Fed has left the benchmark interest rate unchanged nine consecutive times.