A company's SEC filings can be a wealth of information, particularly the annual report (look at financials, President's Letter, Management Comments, footnotes), 10K (line of business, management comments) and proxy statement (executive information). The library receives annual reports and 10Ks in a variety of formats.
Electronic:
Microfiche:
The Library has a collection of annual reports and 10Ks for the New York Stock Exchange companies from 1979-1995. They can be found in the Government Documents area in the basement of the Fondren Library.