The price of crude oil fell more than $2 Monday to its lowest level since early 2009, with Brent crude closing a bit above $40 a barrel.
The decline follows Friday's meeting of the Organization of Petroleum Exporting Countries, where the 13 members announced no agreement to limit production.
Experts say global demand for crude is already about 2 million barrels a day below the current supply. That oversupply may grow as Iran gets out from under international sanctions imposed on its exports.
Some analysts say key OPEC member Saudi Arabia continues to pump oil in a bid to push the price low enough to drive new competitors out of business. Some U.S. producers use advanced techniques like hydraulic fracturing to boost oil output, but the practice costs far more than the traditional techniques that work in the Saudis' abundant oil fields.