A look at the weighted underlying holdings of the The Materials Select Sector SPDR— Fund (XLB) shows an impressive 15.2% of holdings on a weighted basis have experienced insider buying within the past six months. Start slideshow:10 ETFs With Stocks That Insiders Are Buying » Air Products & Chemicals Inc (APD), which makes up 6.74% of the The Materials Select Sector SPDR— Fund (XLB), has seen 2 directors and officers purchase shares in the past six months, according to the recent Form 4 data.