Prospects for big-screen cinema company Imax Corp blurred last night as its stock dropped almost 70 per cent after the company issued a profit warning on Wednesday. Shares of Imax, which operates more than 200 big-screen theatres around the world, including one recently closed in Dublin, plunged 15.25 Canadian dollars, or 70 per cent, to close at Can$6.55 in Toronto after hitting a low of C$6.05 earlier in the day. Investors headed for the doors after the company issued a profit warning late on Wednesday, saying it would post a "modest loss" for the third quarter because of a weakening in the North American exhibition industry and an increase in the money it was spending on developing digital technologies.