Why are global oil prices falling?
The US oil price fell below the symbolic threshold of $50 a barrel for the first time since April 2009, before finishing the day at $50.05.
The price of Brent crude also fell on Monday, dipping 6% to $53 a barrel.
Both Brent crude and US oil, known as West Texas Intermediate crude, have now lost more than half of their value since mid-2014.
Bill Hayton reports.