Many sources of company information identify a company's industry affiliation by a government-defined SIC (standard industrial classification) code or government NAICS (North American Industry Classification System) code. (See SIC vs. NAICS below.) Other sources might use industry names that have been developed for their purpose and do not follow the established NAICS or SIC system.
You will notice, however, that diversified companies do business in different industries or industry sectors. Some available reports distinguish a company's primary industry codes from the secondary codes, which represent less-significant parts of its operations. Other resources and reports simply list the various lines of business in which the company engages without flagging the ones on which a company focuses most heavily.
When identifying competitors for a specific assignment requiring comparison of diversified companies, it usually makes sense to select competitors doing business in the specific market segment (e.g. clothing, telecommunications services, computer consumer goods) pertinent to your project rather than comparing of all facets of each company's operations.
In addition to the resources listed to the left for Industry Overviews, industry statistics can also be found in these sources.
Standard Industrial Classification (SIC) codes are no longer actively being assigned, but are still in use by some publishers. Beginning in 1997, the federal government switched coding systems and is now classifying manufacturing and service industries with a North American Industrial Classification System (NAICS) code in order to promote the comparability of statistics. NAICS codes are more closely aligned with international codes. The SIC/NAICS codes are used in many online and print resources to classify establishments in the same industry. These codes can be very helpful in doing industry research.
One thing to keep in mind: the SIC code has been revised over the years and some code numbers have changed. It is important to be careful when comparing data from different publishers and over a long period of time.