Hedge funds betting on commodities lost the most in almost three years in July as the price-rout deepened.

Funds lost money for a third month, according to the Newedge Commodity Trading Index, which was released to investors Friday and tracks the performance of raw-material trading strategies including equities and physical products. The 1.3 percent decline was the most since October 2012 and the index is down 2.4 percent this year. A slide in everything from oil to metals pushed commodity prices down the most since 2011 in July.

Managers are losing money and commodity funds at Cargill Inc. to Armajaro Asset Management LLP closed this year as China’s slowing economy adds to the global glut in most raw materials. Glencore Plc shares are at a record low, and oil and copper prices dropped to the lowest in six years.

“The path has been far from smooth,” said Kurt Billick, the founder and chief investment officer of Bocage Capital LLC in San Francisco, which manages about $560 million in commodities equities and futures. “In a bear market, it’s much more challenging to hold on to your position long enough for that profit to be realized. Even if you’re short in a bear market, you can get very sharp, vicious short-covering rallies.”

The Bloomberg Commodity Index has tumbled 17 percent this year with more than half of its 22 components stuck in bear markets. It reached the lowest since August 1999 on Monday. The Newedge index, which tracks funds betting on natural resources with assets under management greater than $30 million, was up 1.2 percent last year. It’s at the lowest since August 2010.

Cargill Inc.’s Black River Asset Management unit shut its commodity unit last month and Armajaro Asset Management LLP has closed one of its funds. The founders of Vermillion Asset Management, the commodities hedge-fund firm owned by Carlyle Group, left this year after losses.

“In terms of assets under management, it has been a very difficult time to get money for commodity-related strategies,” Bocage Capital’s Billick said in an interview last week.