In this segment of Friday's Investor Beat, Motley Fool analyst Ron Gross gives investors one stock that he'll be watching closely this week. He takes a look at Arcos Dorados (NYSE:ARCO), which holds the franchise rights to McDonald's (NYSE:MCD) in Latin America and the Caribbean. The company reports earnings next week, and while it has been a long-time holding for Ron in the Motley Fool's Million-Dollar Portfolio service, he sees reasons to be concerned here. The company's store growth is slowing, so he'll be watching closely to see what the company has to say next week.