Copper futures charged up to highs dating back to January 1995 on Wednesday, on a strong demand outlook at the same time supplies are declining and further threatened by labour strikes, traders said.
A drop in already low exchange warehouse inventories coupled with the possibility of strikes at two separate copper facilities, acted as catalysts to buy copper.
Once the red metal pushed higher it set off short-cover buying and drew some funds in to add fresh long positions.
On the COMEX division of the New York Mercantile Exchange, benchmark December copper jumped 1.85 cents to $1.42 per lb., trading from $1.3955 to $1.4250, a new contract high.
On a three-month continuation chart, copper reached its highest level since January 1995. Spot October gained 1.55 cents to $1.4210. Most other contracts also set new highs, rising from 0.35 cent to 1.55 cent. But the highs continued to be achieved on light volume. By 10 am EDT (1400 GMT), COMEX estimated volume at a light 4,000 lots.