12. Business Segments

Business segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision-making group, in assessing performance and deciding how to allocate resources.

As of April 1, 2011, the Company segmented its operations into two new market-facing business units: Wind and Grid. The Company believes this market-centric structure enables it to more effectively anticipate and meet the needs of wind turbine manufacturers, power generation project developers and electric utilities.

·Wind. Through the Windtec brand, the Wind business unit enables manufacturers to field wind turbines with exceptional power output, reliability and affordability. The Company licenses its highly engineered wind turbine designs, provides extensive customer support services and supplies advanced power electronics and control systems to wind turbine manufactures. The Company's design portfolio includes a broad range of drive trains and power ratings up to 10 megawatts. The Company believes its unique engineering capabilities, ranging from bearings to advanced synchronous generators to blades, enables it to provide its partners with highly-optimized wind turbine platforms. Furthermore, these designs and support services typically lead to sales of its power electronics and software-based control systems, which are designed for optimized performance, efficiency and grid compatibility.

·Grid. The Grid segment enables electric utilities and renewable energy project developers to connect, transmit and distribute power with exceptional efficiency, reliability and affordability. The Grid business unit provides transmission planning services that allow us to identify power grid congestion, poor power quality and other risks, which helps the Company determine how its solutions can improve network performance. These services often lead to sales of grid interconnection solutions for wind farms and solar power plants, power quality systems and transmission and distribution cable systems.

Prior to April 1, 2011, the Company segmented its operations through two technology-centric business units: AMSC Power Systems and AMSC Superconductors. AMSC Power Systems included all of its Wind products, as well as Grid products that regulate voltage for wind farm voltage electric utilities, renewable generation project developers and industrial operations. Solutions from the Company's AMSC Superconductors business unit have been incorporated into its Grid business unit. All prior period segment disclosures have been revised to conform to management's current view of the Company's business segments.

The operating results for the two business segments are as follows (in thousands):


	Three months ended
	June 30,
	2011	2010
Revenues:
Wind	$4,262	$83,006
Grid	4,796	14,203
Total	$9,058	$97,209


	Three months ended
	June 30,
	2011	2010
Operating (loss) income:
Wind	($24,370)	$31,339
Grid	(10,552)	(11,764)
Unallocated corporate expenses	(3,405)	(3,494)
Total	($38,327)	$16,081

The accounting policies of the business segments are the same as those for the consolidated Company. The Company's business segments have been determined in accordance with the Company's internal management structure, which is organized based on operating activities. The Company evaluates performance based upon several factors, of which the primary financial measures are segment revenues and segment operating (loss) income. The disaggregated financial results of the segments reflect allocation of certain functional expense categories consistent with the basis and manner in which Company management internally disaggregates financial information for the purpose of assisting in making internal operating decisions. In addition, certain corporate expenses which the Company does not believe are specifically attributable or allocable to either of the two business segments have been excluded from the segment operating income.

Unallocated corporate expenses include stock-based compensation expense of $3.5 million for the three months ended June 30, 2011 and 2010.

Total assets for the two business segments are as follows (in thousands):

	June 30,	March 31,
	2011	2011
Wind	$127,360	$145,464
Grid	64,252	67,081
Corporate assets	202,050	228,664
Total	$393,662	$441,209

The following table sets forth customers who represented 10% or more of the Company's total revenues for the three months ended June 30, 2011 and 2010:


	Three months ended June 30,
	2011	2010


Department of Energy	17%	<10%
Doosan Heavy Industries & Construction Co Ltd.	15%	<10%
Shenyang Blower Works Group Wind Power Co.,Ltd.	13%	<10%
Sinovel Wind Co., Ltd	-%	72%