Canadian National Railway (NYSE: CNI ) is going through a rough patch on the revenue front. The main pressure’s coming from rising tariffs on high-margin merchandise and forest products, plus a mix shift toward lower-margin bulk commodities. That said, the company’sI have over 15 years of experience investing and have provided research services to mid-sized hedge funds with assets under management between $100 and$500 million. I also have had a brief stint as a sell-side analyst. I am now focusing primaril ...