Cannabis, Clean Energy and Commodities: ETF Themes to Watch as 2021's First Quarter Comes to a Close

As the U.S. exchange-traded fund industry nears $6 trillion in assets under management, one market maker says a few hot trades are dominating investors' attention. "Clean energy is still really active. And what's interesting is the marijuana ETFs are active also, very active," Harry Whitton, head of ETF sales trading at Old Mission, told CNBC's "ETF Edge" this week. "Both of those ended the year very strong, and on any given day, when clean energy's up, marijuana's up."