No one country or group of countries has complete control over oil prices, but the Organization of the Petroleum Exporting Countries (OPEC) does exert outsized influence on global supply. The group attempts to control oil prices by setting production quotas for its 13 member countries, which together account for about 40% of global oil production, 60% of global exports, and 80% of proven oil reserves. Saudi Arabia’s advantage within OPEC comes from its preponderance of spare capacity (i.e., unused but easily accessible reservoirs), which allows it to respond relatively quickly to unexpected changes in supply or demand and volatile market prices.