Zoltek Companies, Inc. is a holding company, which operates through wholly owned subsidiaries, Zoltek Corporation, Zoltek Zrt., Zoltek de Mexico SA de CV, Zoltek de Occidente SA de CV, Engineering Technology Corporation (Entec Composite Machines), Zoltek Properties, Inc., and Zoltek Automotive, LLC. Zoltek Corporation (Zoltek) develops, manufactures and markets carbon fibers and technical fibers in the United States. The Company is an applied technology and advanced materials company. Its commercialization of carbon fiber through composites used in a range of commercial products, which it sells under the Panex trade name. In addition to manufacturing carbon fiber, it produces an intermediate product, a stabilized and oxidized acrylic fiber used in flame- and heat-resistant applications, which it sells under the Pyron trade name. During fiscal year ended September 30, 2011, its net sales to Vestas Wind Systems, a wind turbine manufacturer represented % of its net sales.