A look at the weighted underlying holdings of the Invesco S&P MidCap 400 Equal Weight ETF (EWMC) shows an impressive 10.5% 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 Mack Cali Realty Corp (CLI), which makes up 0.29% of the Invesco S&P MidCap 400 Equal Weight ETF (EWMC), has seen 2 directors and officers purchase shares in the past six months, according to the recent Form 4 data.