* U.S. stocks finished lower on Tuesday for a third straight session as investors worried about a rise in interest rates and Apple’s (AAPL.O) shares hit their lowest in over six months. * Atlanta Federal Reserve President Dennis Lockhart told the Wall Street Journal that September may be the right time for the U.S. Federal Reserve to lift interest rates. * The Fed has said it needs to see a sustained economic recovery before it raises interest rates for the first time in nearly a decade.