London - Copper fell to a six-year low as investors added to bearish positions amid expectations for a global supply glut and slowing demand in China, the world’s biggest consumer.

Short positions in the metal increased 39 percent, the most since January 2014, according to US Commodity Futures Trading Commission data released on Monday. A rally for Chinese stocks fizzled on Tuesday after technology and small-company shares plunged, as the Asian nation heads for the slowest economic growth in 25 years. The metal has lost 25 percent this year.

“The copper market has been one of the worst markets I’ve ever seen, copper demand is basically non-existent right now, and all this started when there was a downturn in the Chinese stock market this summer,” Phil Streible, a senior market strategist at RJO Futures in Chicago, said in a telephone interview. “Copper prices are going to continue to travel down to historical levels.”

Copper futures for December delivery fell 0.7 percent to settle at $2.1115 a pound at 1.16pm on the Comex in New York, after touching $2.075 a pound, the lowest since May 2009.

Chile’s Codelco, the biggest copper producer, plans to cut the premium that purchasers must pay on sales to China by the most since 2009 to try to boost shipments to the largest consumer and counter slowing demand, according to two buyers. The copper market in 2015 will have a production surplus of 78 000 metric tons, even as mining companies cut output, according to CRU consultant Matthew Wonnacott.

Glencore and Freeport-McMoRan are among miners that cut back their production of copper and other metals. A gauge of the largest base-metals producers tracked by Bloomberg Intelligence is near the lowest since March 2009, even after snapping an eight-session drop on Tuesday.

“It’s all about sentiment,” Casper Burgering, an analyst at ABN Amro Bank in Amsterdam, said by phone. “Bad signals from China are directly translated into base metal price directions and any good news is ignored.”

Added to that is the strengthening dollar on expectations the US will raise interest rates, making metals priced in the currency more expensive for buyers elsewhere.

Copper for delivery in three months fell 0.1 percent to $4,684 a ton ($2.12 a pound) on the London Metal Exchange. Also on the LME, zinc, lead and nickel declined, while aluminium gained. Tin was unchanged.