Market Vectors Steel ETF ( SLX) -3.2% China announced that it was paring back its growth prospects, injecting a hearty dose of global growth-related uncertainty into the markets. In response, industries that perform best during periods of optimism are suffering standout losses. SLX and the Market Vectors Coal ETF ( KOL) are among the heaviest hit. All prices as of 2:11 PM EST. Written by Don Dion in Williamstown, Mass.