Global trading of oil and gas means international markets are more open than at any previous time. As a result, the oil industry oligopoly is being deconstructed and vertically integrated MNCs are being reconstituted to address this fact. In parallel, emergent MNCs in the form of National Oil Companies are now entering the competitive arena. Traditionally dominant MNCs are adopting new operating models focused on technological and financial strength. We examine changes in the once-dominant industry paradigm of vertical integration using several theoretical lenses. These include transaction-cost economics, the resource-based view and institution theory. The giant MNCs operated globally for decades and are an important variant of the MNCs studied in strategic management literature. We suggest the current theoretical models do not explain sufficiently how these MNCs respond to current changes and by using industry observation we contribute to modernization of this literature.