From Mad Money:
Jim, is there an ETF that tracks alternative energy stocks? — Gus from Long Island, N.Y.
James J. Cramer: One popular ETF that tracks alternative energy plays is the Powershares Wilderhill Clean Energy Portfolio (PBW:Amex) . It holds 36 stocks in the alternative energy business, including Capstone Turbine (CPST:Nasdaq) , Plug Power (PLUG:Nasdaq) and UltraLife Batteries (ULBI:Nasdaq) , and the diversity may help protect investors from some of the wild swings you see in these types of stocks.