A firm such as Chevron in petroleum spans wide segments of the valuechain in which it operates, from oil exploration to service stations, but itdoes not span the entire chain. Fifty percent of the crude oil it refinescomes from other producers, and more than one third of the oil it refines issold through other retail outlets. Also, Chevron is not in the auto businessat all, the major user of gasoline. More narrowly, a firm such as MaxusEnergy is only in the oil exploration and production business. The LimitedStores are big "downstream" in retail outlets but own no manufacturingfacilities. Reebok Is a famous shoe brand, but the firm owns very few retailoutlets. Reebok does, however, own its factories.