The best performing sector as of midday Friday is the Materials sector, up 1.1%. Within that group, Allegheny Technologies (NYSE: ATI) and Freeport-McMoran Copper & Gold (NYSE: FCX) are two large stocks leading the way, showing a gain of 5.9% and 3.1%, respectively. Among the high volume ETFs, one ETF closely following materials stocks is the Materials Select Sector SPDR ETF (AMEX: XLB), which is up 1.0% on the day, and up 10.83% year-to-date. Allegheny Technologies meanwhile, is up 0.87% year-to-date, and Freeport-McMoran Copper & Gold, is down 18.60% year-to-date. Combined, ATI and FCX make up approximately 4.6% of the underlying holdings of XLB.