Company research can be subdivided into to part, Public Companies and Private Companies.

For Public Companies, use he following two sources to start.

• Mergent Intellect is a great database for in-depth information on publicly traded companies.  This source is useful for financial statements, SEC filings, ratios, industry benchmarks, etc., as well as investment analyst reports.
• Standard &  Poor's NetAdvantage is an excellent source for company and industry research, including financial and ratio analysis.  It contains the former Standard & Poor's Industry Surveys and Stock Reports.  This source also includes mutual fund/ETF and bond information, investment research reports, stock screenings and charting tools.

For Private Companies, start with the database,  Mergent Intellect. as well.  It includes a broad range of industry reports.

• ABI/Inform Complete - ProQuest contains business and in depth company and industry articles from scholarly, trade and news publications.Also, found are reports from major and smaller, niche industries.
• Business Premium ProQuest, the link goes to ProQuest One Business, an updated version of Business Premium.
• Business Source Elite provides full text of more than thousands of business publications, including more than a thousand peer reviewed journals.  It is  comprehensive database that covers all disciplines of business including management, finance, marketing and international trade.  It also contains company, industry and country reports, SWOTs and market research reports.
• IBIS World database provides in-depth industry analysis for 700+ U. S. industries and hundreds of international industries.  Searchable by keyword, company name, and NAICS codes.  Reports average 25-30 pages and contain key statistics, market characteristics, segmentation,  industry conditions, industry performance, key competitors, key factors, and industry outlook.
• ProQuest One Business includes all of the content from the Business Premier Collection (ABI/INFORM, J.P. Morgan Research, Entrepreneurship Database, Accounting Tax & Banking Collection, Business Market Research Collection) as well as over 20,000 e-books.Company, industry and country reports from providers such Fitch Solutions and Economist Intelligence Unit; and in-depth analyst reports from J. P. Morgan.
  • Scholarly journal and ebook coverage from hundreds of publishers
  • Full text of the three major global business news sources: the Wall Street Journal,
  the Economist and the Financial Times
  • A robust collection of video – including interviews with business leaders,
  case studies and trainings
• Standard & Poor's NetAdvantage provides excellent industry research on financial and ratio analysis.