Fed's Powell cautions a 'sustained period' of slow growth

STORY: The U.S. central bank has raised rates at its last six meetings beginning in March, marking the fastest round of rate increases since former Fed Chair Paul Volcker's fight to control inflation in the 1970s and 1980s. The policy decision set the target federal funds rate in a range between 3.75% and 4.00%, the highest since early 2008.

Powell also cautioned against any sense the central bank will soon move to the sidelines with interest rate rises.