Copper plummeted to a six month low on rising stocks, a soft technical picture and as several commodities across the board fell, which dampened sentiment.

The red metal is leading some other base metals lower, while platinum is near a seven month low, gold is down after hitting a fresh six-week low and oil is trading beneath $120 and copper down after losing 4 percent Monday. The stronger dollar is weighing heavily on commodities amid the slow demand summer season. The dollar was higher as investors also braced for the Federal Reserve's policy decision later in the day with the focus on the central bank's post-meeting statement for clues on the monetary policy outlook.

LME copper stocks rose 2,550 tonnes to 148,750, up over 20 percent in the past month and their highest since February.

"While this is arguably a seasonal build up ... the dominant warrant holder in copper has failed to keep pace with rising inventory, allowing its position to slip," said analyst Leon Westgate at Standard Bank in a research note.

At 11:19 a.m., three-month copper on the LME was trading at $7,625 per tonne from $7,605 at the close Monday. Earlier in the session copper hit $7,530 per tonne, its lowest value since February 2.

"Bear market trading continues prompting metals prices to fall further across the board with platinum, copper and gold seen as major losers. The selling across the board for commodities and mining equities alike looked like a bear raid," said John Meyer, Fairfax analyst. "While metals prices are vulnerable to falls in the current environment we believe the market should see a significant rally in September as consumers and traders rebuild stock levels to support ongoing global industrial activity."

Elsewhere on the LME, aluminium was at $2,888 per tonne from $2,882, nickel dropped to $17,725 per tonne from $18,025, zinc was at $1,775 per tonne from $1,767, tin tumbled to $20,150 per tonne from $20,600 and lead ticked up to $2,005 per tonne from $1,995 at the close Monday. – Forbes