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. The opinions expressed are those of the author and do not represent the views of TheStreet or its management. NEW YORK ( TheStreet) - Clean Edge and Nasdaq's three benchmark clean-tech stock indexes experienced mixed movement last week, as the Nasdaq Clean Edge Green Energy Index ( CELS) was up 1.75 percent, the Nasdaq OMX Clean Edge Global Wind Energy Index ( QWND) lower by 0.16 percent, and the Nasdaq OMX Clean Edge Smart Grid Infrastructure Index ( QGRD) gaining 0.54 percent from the previous week. The overall market moved slightly higher. The S&P 500 gained 1.39 percent and Nasdaq was up 1.45 percent - while AMEX Oil retreated 0.03 percent from the previous week. CELS - up 1.75 percent for the week and 23.13 percent 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 50 total component securities, 31 experienced gains, 16 lost ground, and three ended the week unchanged. CELS' best performer for the week was LED and solar manufacturing equipment provider Veeco Instruments ( VECO) , gaining 17.72 percent. Rounding out the top five CELS performers were wind energy product and service provider Broadwind Energy ( BWEN), up 12.57 percent; electronic materials provider Rubicon Technology ( RBCN), higher by 11.50 percent; carbon fiber manufacturer Zoltek Companies ( ZOLT), up 8.94 percent; and OLED technology developer Universal Display ( PANL), 8.47 percent higher for the week. CELS' worst performer last week was demand management firm EnerNOC ( ENOC), declining 15.19 percent. Other worst performers included demand management service provider Comverge ( COMV), losing 9.30 percent; renewable energy project integrator Satcon Technology ( SATC), down 8.69 percent; solar energy product manufacturer Energy Conversion Devices ( ENER), retreating 6.19 percent; and power energy management device maker Power Integrations ( POWI), 4.22 percent lower for the week. QWND - 0.16 percent lower last week and 22.28 percent 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, nine saw gains, eight experienced losses, and one was unchanged for the week. QWND's best pure play performer for the week was Zoltek Companies, up 8.94 percent. Other top pure play performers included renewable energy project developer EDP Renovaveis ( EPDR), gaining 6.07 percent; wind power project owner and operator Japan Wind Development Company (2766), rising 3.31 percent; renewable energy project developer Iberdrola Renovables ( IBR), up 1.44 percent; and renewable energy developer EDF Energies Nouvelles ( EEN), up 1.08 percent for the week.