The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.

NEW YORK ( Clean Edge ) -- Clean Edge and Nasdaq's three benchmark clean-tech stock indices each retreated last week, with the Nasdaq Clean Edge Green Energy Index (CELS) down 3.67% , the Nasdaq OMX Clean Edge Global Wind Energy Index (QWND) lower by 1.22% , and the Nasdaq OMX Clean Edge Smart Grid Infrastructure Index (QGRD) falling 2.25% from the previous week.

The overall market also moved lower -- the S&P 500 lost 1.72% and NASDAQ was down 1.87% -- while AMEX Oil lost 0.20% from the previous week.

CELS -- down 3.67% for the week and 21.28% higher than a year ago -- tracks U.S.-listed clean-energy companies and is divided into four categories: advanced materials; energy intelligence; energy storage and conversion; and renewable electricity generation and renewable fuels. Of the 49 total component securities, 10 experienced gains and 39 lost ground.

CELS' best performer for the week was biomaterials developer Metabolix ( MBLX), gaining 5.30% . Rounding out the top five CELS performers were electronic materials provider Rubicon Technology ( RBCN), up 4.88% ; electric car maker Tesla Motors ( TSLA), higher by 1.86%; ethanol producer Green Plains Renewable Energy ( GPRE), up 1.22% ; and demand management firm EnerNOC ( ENOC), 1.06% higher for the week.

CELS' worst performer last week was renewable energy project integrator SatCon Technology ( SATC), declining 15.84% . Other worst performers included geothermal power developer Ormat Technologies ( ORA), losing 14.14% ; solar cell manufacturer JA Solar ( JASO), down 13.73% ; power conversion technology developer Vicor Corporation ( VICR), retreating 13.19% ; and wind energy product and service provider Broadwind Energy ( BWEN), 12.57% lower for the week.

QWND--- 1.22% lower last week and 20.78% lower in the last 12 months -- includes companies that are primarily manufacturers, developers, distributors, installers, and users of energy derived from wind sources. Of QWND's 18 pure play components, five saw gains and 13 experienced losses.

QWND's best pure play performer for the week was renewable energy project developer Gamesa Corporacion Tecnologica ( GAM), up 7.08% . Other top pure play performers included wind turbine maker Vestas Wind Systems ( VWS), gaining 6.52% ; wind turbine maker REpower Systems ( RPW), rising 4.77% ; advanced composite materials developer Gurit Holding (GUR), up 1.19% ; and wind turbine manufacturer Nordex ( NDX), up 1.07% for the week.

QWND's worst pure play performers were wind project developer Infigen Energy ( IFN), losing 14.29% ; wind turbine gear transmission provider China High Speed Transmission Equipment Group (0658), down 7.19% ; carbon fiber material developer Zoltek Companies (ZOLT), losing 7.02% ; wind turbine gearbox maker Hansen Transmission International (HSN), declining 5.02% ; and wind farm owner and operator China Longyuan Power Group (0916), falling 4.67% from the previous week.

QGRD -- 2.25% higher from the previous week and 17.69% higher than a year ago - is composed of companies that are primarily involved in the electric grid; electric meters, devices, and networks; energy storage and management; and enabling software used by the smart grid and electric infrastructure sector. Of 22 pure play components, three experienced positive movement while 19 saw losses.

QGRD's best pure play performer was Spanish transmission grid owner and operator Red Electrica ( REE), up 1.42% for the week. Rounding out the top five pure play performers were EnerNOC, gaining 1.06% ; smart grid service provider PowerSecure ( POWR), rising 0.40% ; electrical equipment manufacturer AZZ (AZZ), 0.25% lower; and transmission grid owner and operator ITC Holdings ( ITC), lower by 0.48% .

QGRD's worst performers included SatCon Technology, losing 15.84% ; demand energy management service provider Comverge ( COMV), down 8.32% ; utility specialty contractor Quanta Services ( PWR), down 6.15% ; utility wire and cable provider General Cable ( BGC), lower by 4.79% ; and utility network provider Esco Technologies ( ESE), falling 4.64% .

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