Thinking green (investments)? Why it rarely pays to buy niche ‘thematic’ ETFs By: MarketWatch April 22, 2021 at 10:41 AM EDT You're better off purchasing a sector ETF with diversified holdings. Read More >> Related Stocks: Ballard Power Sys Bloom Energy Corp Cl A Direxion Hydrogen ETF ETF Series Defiance Next Gen H2 ETF ETFMG Alternative Harvest ETF Plug Power Inc Solar Invesco ETF Tesla, Inc. US Copper Wilderhill Clean Energy Invesco ETF