Aug. 31 (Bloomberg) –Copper swung between gains and losses, heading for the biggest monthly drop since May 2010 as worsening U.S. consumer confidence stoked concern that growth may stall. Tin was set for the largest loss since October 2008.

Three-month delivery copper on the London Metal Exchange lost as much as 0.5 percent to $9,114 a metric ton before trading at $9,202.50 at 3:33 p.m. Singapore time. The price touched $9,225 yesterday, the highest since Aug. 5. The metal has fallen 6.5 percent this month, the first such decline in three months.

The Conference Board's index of consumer confidence in the U.S., the world's second-largest copper user, slumped to 44.5, the weakest since April 2009. It was the biggest point drop since October 2008, falling from a revised 59.2 reading in July, figures from the New York-based research group showed yesterday. A separate report showed home prices declined for a ninth month.

The market is under downward pressure from “concern over European sovereign debt and U.S. growth and unemployment,” Nick Trevethan, senior commodities strategist at Australia & New Zealand Banking Group Ltd., said today by phone from Singapore.

A further drop in price would be limited as supplies are likely to decline with an 18 percent drop in Chilean output and a potential strike at Indonesia's Grasberg mine, he said.

Japan Output
Industrial production in Japan rose less than expected in July, signaling that the nation's recovery from the March 11 earthquake and tsunami is losing momentum as the yen gains and overseas demand slows. In South Korea, industrial output expanded at the slowest pace in 10 months as weakness in global growth threatens the outlook for exports.

Factory output in Japan, the world's third-largest economy, increased 0.6 percent in July from June, the slowest gain since March, the Trade Ministry said in Tokyo today. The median estimate of 28 economists surveyed by Bloomberg News was for a 1.4 percent gain after a 3.8 percent increase in June.

Copper for November delivery on the Shanghai Futures Exchange was little changed at 68,190 yuan ($10,670) a ton.

Aluminum in London advanced 0.4 percent to $2,435.25 a ton. Still, the metal has slumped 7.2 percent this month, the biggest fall since May 2010. Zinc gained 0.2 percent to $2,290 a ton. Lead rose 0.4 percent to $2,568 a ton, after dropping as much as 1.6 percent.

Nickel added 0.2 percent to $21,950 a ton after dropping as much as 0.7 percent and tin jumped 1 percent to $24,250 a ton. Tin has slumped 14 percent this month, the biggest loss since October 2008.