Business: Marathon Petroleum Corporation (MPC) is a large-scale, geographically-diversified and highly-integrated refining, marketing and midstream company. MPC is the nation's largest refiner, with a crude oil refining capacity of more than 3 million barrels per calendar day in its 16-refinery system. MPC's high-quality, nationwide retail and marketing business includes approximately 3,900 company-owned and -operated stores and 7,800 branded locations. MPC owns the general partners of MPLX LP and Andeavor Logistics LP, two strong, customer-focused midstream master limited partnerships.