The downstream business of refining crude oil and marketing products to end-users has long been a valuable, if occasionally out of fashion, part of the oil company portfolio. Today, the downstream business is attractive to a range of different types of owners. These companies seek out downstream profits from processing new low-cost crude oils, capturing product growth in emerging markets, and integrating further into petrochemical. Still, there is the ever-present concern that increasingly stringent policies aimed at decarbonization and local air quality will affect the downstream pillar of the oil business.