81 AGL Energy Limited Annual Report 2012 The consolidated entity has four reportable operating segments  as follows: No operating segments have been aggregated to form the above  reportable operating segments. In the segment financial results, the ‘Other’ category consists of  the various Corporate activities which includes the head office and  central support functions. Corporate is not considered a reportable  operating segment.  The measurement of segment results is in line with the basis of  information presented to the Board of Directors for internal  management reporting purposes. The performance of each  segment is measured based on their ‘Operating EBIT contribution’  to the consolidated entity. Certain items of income and expense  are excluded from the segment results to show a measure of  underlying performance. These items include changes in fair value  of financial instruments and significant items. Transfer prices between operating segments are on an arm’s- length basis in a manner similar to transactions with third parties.  Inter-segment revenue is eliminated on consolidation. The accounting policies of the reportable segments are the same  as the consolidated entity’s accounting policies. Information regarding the consolidated entity’s reportable  segments is presented below. Segment financial results > Retail Energy  is responsible for selling natural gas, electricity and  energy-related products and services to residential and small  business customers. > Merchant Energy  is responsible for developing, operating  and maintaining power generation assets and managing the  risks associated with the procurement and delivery of gas and  electricity for its wholesale portfolio and for the Retail Energy  segment. Merchant Energy also sells natural gas and electricity  to business customers and provides energy efficiency and carbon  management services. Merchant Energy is also now responsible  for managing and maintaining the Loy Yang A power station and  adjacent brown coal mine. > Upstream Gas  Is responsible for investments and operations  in gas exploration, development and production tenements,  development and operation of gas storage facilities, as well  as for exploration and development of geothermal renewable  energy sources. > Energy Investments  includes equity accounted investments  in the ActewAGL Retail Partnership and Diamantina Holding  Company Pty Limited. The equity accounted investment in  Great Energy Alliance Corporation Pty Limited (GEAC) was  also included in this segment up until 29 June 2012, when AGL  completed the acquisition of GEAC, increasing its ownership from  32.54% to 100%. GEAC owns the Loy Yang A power station  and adjacent brown coal mine which are now reported in the  Merchant Energy operating segment.