Who owns most of the world oil supply?
During World War II (1939–1945) – control of oil supply from Baku and Middle East played a huge role in the events of the war and the ultimate victory of the allies. Cutting off the oil supply considerably weakened Japan in the latter part of the war. After World War II ended, the countries of the Middle East took the lead in oil production from the United States. Important developments since World War II include deep-water drilling, the introduction of the Drillship, and the growth of a global shipping network for petroleum relying upon oil tankers and pipelines. In 1949, first offshore oil drilling at Oil Rocks (Neft Dashlari) in the Caspian Sea off Azerbaijan eventually resulted in a city built on pylons. In the 1960s and 1970s, multi-governmental organizations of oil–producing nations OPEC and OAPEC played a major role in setting petroleum prices and policy. Oil spills and their cleanup have become an issue of increasing political, environmental, and economic importance.
What group owns most of the world's oil supply?
OPEC
Petroleum industry
No context provided
What company owns most of the world's oil supply?
Saudi Aramco
Petroleum industry
https://en.wikipedia.org/wiki/Petroleum%20industry
The Organization of the Petroleum Exporting Countries (OPEC, /ˈoʊpɛk/ OH-pek) is an intergovernmental organization or cartel of 13 countries. 
OPEC
The current OPEC members are the following: Algeria, Angola, Equatorial Guinea, Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, the Republic of the Congo, Saudi Arabia (the de facto leader), the United Arab Emirates and Venezuela.
OPEC
The Organization of the Petroleum Exporting Countries is an intergovernmental organization or cartel of 13 countries. In the 1960s and 1970s, multi-governmental organizations of oil–producing nations OPEC and OAPEC played a major role in setting petroleum prices and policy. The current OPEC members are the following: Algeria, Angola, Equatorial Guinea, Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, the Republic of the Congo, Saudi Arabia (the de facto leader), the United Arab Emirates and Venezuela. Saudi Aramco owns most of the world's oil supply.