How the U.S. and OPEC Drive Oil Prices

http://www.nytimes.com/interactive/2015/09/30/business/how-the-us-and-opec-drive-oil-prices.html?_r=0

The global price of a barrel of oil remains near its lowest point since the depths of the 2009 recession — a result of a supply glut and battle for market share between the OPEC oil cartel and the United States, which has shifted toward the role of global swing producer.