Alimentation Couche-Tard sells fuel for you and your car on both sides of the US-Canada border. It's the second-largest convenience store operator in North America and the leader in Canada with some 6,000 outlets: Couche-Tard in Québec; Mac's in central and western Canada; and more than 4,600-plus Circle K shops in more than 40 US states and a dozen countries. (It bought the Circle K chain in the US from ConocoPhillips in 2003.) Most of its sales are rung up in the US. Alimentation Couche-Tard, French for "food for those who go to bed late," sells gas at more than three-quarters of its stores. The fast-growing chain is known for expanding, at home and abroad, through splashy acquisitions.