Copper ETF

The iPath Dow Jones-UBS Copper ETN (NYSEArca: JJC) is down over 5% the past month.

The stock market rally and economy are missing what historically has been a key element — a house call from “Dr. Copper,” writes Jeff Cox at CNBC.com.

“The industrial metal has earned its nickname for being a reliable barometer on growth and, in turn, a sign to investors that it’s safe to buy the types of industrial stocks normally associated with a robust market,” Cox notes.

Copper’s recent decline suggests “either the market rally and hopes for future growth may be too high, or that the ‘doctor’ may be guilty of malpractice.”

From a technical perspective, Barclays analysts forecast copper may see additional weakness after breaking through so-called triangle support, Bloomberg News reported Wednesday.