The industry, sector and S&P 500 numbers on the Ratios page are market capitalization-weighted averages of all the companies in those groups. Industries and sectors are determined by a company's placement in the Reuters Business Sector Schema, (RBSS) while the components of the S&P 500 are determined by Standard and Poors and can be found at their Web site. These averages may or may not correspond to those numbers reported elsewhere in Reuters or as presented by other data providers.
Users who may want to make adjustments of their own are reminded that for many of these data points the raw numbers used to calculate the figures on the Ratios page are available on the Reuters.com Web site. For example, the coal industry components can be found at:http://www.reuters.com/sectors/industries/rankings?view=size&industryCode=164