MPLX is a master limited partnership (MLP) formed by refining giant Marathon Petroleum to own and operate midstream energy infrastructure and logistics assets. The MLP has two focus areas: crude oil and products logistics, and natural gas and natural gas liquids (NGL) services. The company's pipelines, processing plants, storage terminals, and export facilities generate fairly stable earnings, backed by government-regulated rate structures and long-term contracts with high-quality customers, such as Maratho ...