Aug 7 (Reuters) - A tumble in shares of energy companies pressured Canada's main stock index at the open on Wednesday, as crude prices slumped to a seven-month low.
* At 9:30 a.m. ET (13:30 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 56.79 points, or 0.35%, at 16,092.7.