Feb 11 (Reuters) - Canada’s main stock index fell at open on Thursday, dragged down by stocks of cannabis companies, a day after hitting a record high on the back of a sharp rally in the sector fueled by Reddit-inspired retail investors. * At 9:33 a.m. ET (14:33 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 28.28 points, or 0.15%, at 18,429.5. (Reporting by Shivani Kumaresan in Bengaluru; Editing by Vinay Dwivedi)