Copper prices are unraveling as global economic uncertainty returns to haunt risk assets.
After an optimistic start to the year, Europe's recovery hopes were dashed by weak manufacturing data; there are fears the U.S. sequestration will undermine growth, and China is showing signs of weakness.
And the minutes from the last Federal Reserve policy setting meeting showed divisions about when the central bank may start to wind down its bond-buying program.
"When there's uncertainty, fund managers pull the trigger," George Gero, vice president of global futures at RBC Capital Markets, said of the recent decline in copper.