‘Copper top’ could spell weakness for broad market By: MarketWatch March 13, 2011 at 12:01 PM EDT Tumbling copper prices hurt exchange-traded funds tracking commodities, materials stocks and Chile’s market. Read More >> Related Stocks: Chile Ishares MSCI ETF Freeport-McMoRan MATERIALS Materials Alphadex ETF FT Materials ETF Vanguard Newmont Mining US Basic Materials Ishares ETF