Copper ended down for a second straight day on Thursday, after data showing a contraction in China's vast manufacturing sector lessened some demand optimism in the world's top metals consumer.
"The Chinese numbers were very negative; that's what is keeping metals subdued," said Edward Meir, analyst at MF Global.
In New York, the key September COMEX contract shed 5.25 cents or 1.2 percent to settle at $4.3835 per lb.
Despite the loss, copper prices in London and New York are up about 14 percent from an early-May trough, and just 5 percent away from their respective records at $10,190 and $4.63.