Altria is the parent company for Philip Morris USA, the PM brands of cigarettes occupy 50% of all the cigarettes sold in the US.
Altria is the parent company for Kraft Foods, but Kraft Mac & Cheese, as a brand family has a 50+ share of that category.
Kraft Foods itself does not have a 50% share for all its brands but it does have a 50 share for several (Oscar Meyer, Life Saver, Oreo also come to mind within their respective categories.)