Invesco WilderHill Clean Energy ETF(AMEX:PBW)

PBW is highly diverse in scope, reaching beyond just industry pure-plays like wind, solar, biofuels and geothermal companies, to include companies based on their perceived relevance to the renewable energy space. The fund's proprietary selection process and its mandate to hold only US-listed companies select companies that are perceived to benefit from the societal transition or advancement toward clean energy and conservation. Included as well are companies developing and selling energy technologies and energy management services to address efficiency and environmental issues, along with fossil fuel resource abundance concerns. PBW follows a tiered, equal-weighting structure and caps each holding at 4%. The index is reconstituted and rebalanced quarterly.