The bashing in copper exchange traded funds Monday highlighted investor concerns over the global economy and the debt situation in Europe. ETFs that invest in copper futures and miner stocks lost more than 3% amid the selling.

The $200 million iPath Dow Jones-UBS Copper ETN (NYSEArca: JJC) was down more than 3%, as were First Trust ISE Global Copper (NasdaqGM: CU) and Global X Copper Miners ETF (NYSEArca: COPX). Sector bellwether Freeport-McMoRan (NYSE: FCX) was off 3%.

Copper prices are seen as a leading indicator of the global economy because the commodity is widely used in building and industry.

Richard Ross, Global Technical Strategist at Auerbach Grayson, in a May 11 note said the rebound in commodities after the initial sell-off was likely an “ephemeral bounce, not the time to pounce, and we continue to recommend a more cautious posture as this shot across the bow runs its course.”

He said the BRIC countries – Brazil, Russia, India and China – “remain on the brink, Dr. Copper is rolling, the dollar has reached a tipping point, bond prices are ripping and yields are slipping towards 3%,” according to the report earlier this month. “In addition, negative divergences are registering as we enter a seasonably weak period with many markets into resistance at multi-year highs; a potential recipe for a sharp sell-off.”