A look at the weighted underlying holdings of the ProShares S&P Kensho Cleantech ETF (CTEX) shows an impressive 26.6% 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 » Sunnova Energy International Inc (NOVA), which makes up 2.69% of the ProShares S&P Kensho Cleantech ETF (CTEX), has seen 3 directors and officers purchase shares in the past six months, according to the recent Form 4 data.