The Materials Select Sector SPDR (NYSEArca: XLB) and other materials ETFs are performing admirably this year. For example, XLB, the largest materials ETF by assets, is up 19% year-to-date. Rivals to XLB include Vanguard Materials ETF (NYSEArca: VAW) and Fidelity MSCI Materials Index ETF (NYSEArca:...