NOTHING COSTS MORE THAN IT USED TO:

Standard Chartered analyst Judy Zhu was startled when she made her regular round of China's copper warehouses.

The stacks of copper slabs inside the warehouses in Shanghai last month had grown by 20% since July, she estimated. Some piles had reached the ceiling. So much copper had been sent into storage that the metal was being lined up outside some buildings. The earth beneath some huge piles was beginning to crack under their weight.

"There's much more metal than we had expected," Ms. Zhu said in an interview. Typically, copper stocks fall over the summer due to a seasonal peak of demand from air-conditioner makers and power-grid builders. 

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