Exchange traded funds tracking oil and copper fell sharply Wednesday on worries a slowing global economy will cut demand for the key commodities.

The iPath Dow Jones-UBS Copper Subindex Total Return ETN (NYSEArca: JJC) was down more than 6% at last check, while U.S. Oil Fund (NYSEArca: USO) fell 3%. Both exchange traded products were in the red following Tuesday’s rally, which was fueled by hopes that Eurozone leaders will solve the debt crisis.

Many investors watch copper ETFs since the industrial metal is seen as a leading indicator for the global economy due to its wide uses in construction and industrial applications. [ETF Chart of the Day: Copper]

“The copper market has cracked and has followed other financial markets lower,” Citi analysts said, in a Dow Jones Newswires report. The analysts expect copper prices to slip, “driven by a weakening global economic outlook and financial uncertainty.” [Copper ETFs Fall to 14-Month Low]

In oil, crude futures were under pressure but managed to hold $81 a barrel.

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