Oil fell almost $3 Friday to close the week near $40 a barrel, the lowest closing price in four years, Bloomberg reported.
Benchmark light sweet crude futures closed at $40.81 on the New York Mercantile Exchange, and fell 25% in the last week alone, Bloomberg said.
The decline was in part due to lower economic indicators including an uptick in the U.S. unemployment rate to 6.7% Friday, Bloomberg said.
Diesel and gasoline prices have plummeted to well below $3 and $2 a gallon, respectively, since the highs near $5 and $4, respectively, in July.
The Energy Department comes out with its weekly survey of filling station prices on Monday.