US copper prices ended lower on Thursday, erasing earlier gains as volatility in the currency market weighed on broader sentiment, but the metal's tightening market balance limited the losses. Copper for December delivery shed 1.20 cents to end at $3.7815 per lb on the COMEX metals division of the New York Mercantile Exchange. Trading ranged from $3.7655 to $3.85.
Earlier this week, benchmark December copper rallied to a 27-month peak at $3.88. COMEX estimated final copper futures volume at 46,392 lots, up from prior tally of 38,406 lots. Open interest jumped 2,245 lots to a record 165,100 contracts as of October 20.