A look at the weighted underlying holdings of the Vanguard S&P Small-Cap 600 ETF (VIOO) shows an impressive 13.0% 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 » Arconic Corp (ARNC), which makes up 0.30% of the Vanguard S&P Small-Cap 600 ETF (VIOO), has seen 4 directors and officers purchase shares in the past six months, according to the recent Form 4 data.