TORONTO, May 8 (Reuters) - Canada's main stock index opened higher on Monday in broad gains helped in part by financial stocks, but Home Capital Group shares fell sharply on news its account balance halved and said it had suspended its dividend. Toronto Stock Exchange's S&P/TSX composite index .GSPTSE rose 23.74 points, or 0.15 percent, to 15,605.78 shortly after the open. Materials were the only group among the index's 10 key sectors to retreat.