EIA – “The world oil market is complicated. Companies are often thought of as the primary actors in this market, but governments play a large role as well. To answer this question, we’ll explore the role oil companies and governments play in the world oil market and their interactions.

• The United States has no national oil company. The largest three U.S.-based international oil companies (ExxonMobil, Chevron, and ConocoPhillips) are accountable to their shareholders, not the United States government.
• In 2010, the world’s top three national oil companies (NOCs) by share of world production were: Saudi Aramco (12%), National Iranian Oil Company (NIOC) (5%), and PdVSA (Venezuela) (4%).
• The top three international oil companies (IOCs) by share of world production were: Exxon Mobil (3%), BP (3%), and Royal Dutch Shell (2%)”