CANADA STOCKS-TSX little changed ahead of Yellen speech

TORONTO, Aug 21 (Reuters) - Canada's main stock index was little changed on Thursday as investors awaited a speech from U.S. Federal Reserve Chair Janet Yellen to scan for clues about the central bank's outlook for interest rates. The Toronto Stock Exchange's S&P/TSX composite index was down 5.86 points, or 0.04 percent, at 15,556.09. Seven of the 10 main sectors on the index were in the red. (Reporting by John Tilak; Editing by Chizu Nomiyama)