Aug 28 (Reuters) - Canada's main stock index opened

lower on Wednesday due to losses in energy and mining stocks,

while investors digested upbeat earnings from major domestic

lenders and awaited Nvidia's quarterly earnings.

At 9:31 a.m. ET (13:31 GMT), the Toronto Stock Exchange's

S&P/TSX composite index was down 74.67 points, or

0.32%, at 23,185.29.