Copper sank to its lowest price since October 2011 on Wednesday, as the outlook for the global economy continued to weaken.
Copper for May delivery fell 11.8 cents to $3.1875 a pound, a drop of 3.6 percent. It's down 16 percent since Feb. 1, when it hit a recent high of $3.78 a pound.
Prices for other industrial metals and energy futures also fell. Crude oil extended a weeklong slide, losing $2.04 to $86.68 a barrel. That's down almost $8 a barrel from a week ago.
The latest blow to investors' confidence came when the International Monetary Fund lowered its outlook for the world economy on Tuesday. The IMF said government spending cuts will slow U.S. growth and keep Europe in a recession this year.
Also this week China reported economic growth that was slower than investors expected. China is a huge importer of basic materials like copper, so a drop in demand from that country would push prices for commodities lower.
Copper prices tend to move sharply when the outlook for global economic growth changes. That's because demand for the metal rises and fall sharply when construction of homes and manufacturing of goods like electronics, which uses a lot of copper, increases or decreases.
The prices of palladium and platinum also are strongly affected by news about and investors' expectations of auto sales, because the metals are used to make catalytic converters for cars. The prices of both metals fell Wednesday after the European automakers association reported that new car sales across Europe slid 10 percent in the first quarter to 2.9 million.
Palladium for June delivery fell $16.80 to $661.40 an ounce, while platinum for July delivery fell $15.20 to $1,435.40 an ounce.
Gold, which had its biggest one-day drop in 30 years on Monday, edged down. The June contract fell $4.70 to settle at $1,382.70. Silver for May delivery fell 32.10 cents to $23.307 an ounce. On Monday it plunged $140 an ounce, or 9 percent.
In agricultural commodities, wheat fell half a cent to $7.0725 a bushel, corn lost 2.75 cents to $6.605 a bushel and soybeans rose 10.75 cents to $14.225 a bushel
Energy futures fell broadly. The latest catalyst to push oil lower was an Energy Department report that suggested drivers aren't filling their tanks as much as they did a year ago.
Wholesale gasoline fell 5 cents to $2.73 a gallon. Heating oil fell 7 cents to $2.73 a gallon and natural gas rose 5 cents to $4.21 per 1,000 cubic feet.