I just started reading Shaping the Industrial Century: The Remarkable Story of the Evolution of the Modern Chemical and Pharmaceutical Industries, and in the preface, Alfred Chandler says:
No source was more valuable than Hoover's Handbooks, produced annually since 1990 for both American and non-American companies. Each handbook includes a ten-year review of the companies' financial statistics and a portfolio of their major product lines, with percentage of sales and income from these lines as well as a brief resume of their history. Hoover's Handbooks certainly remain a reliable basic source for business and economic historians to carry out their central analytical tasks.
It looks like these may be a great way to get a quick overview of a bunch of different businesses, and used copies of the 2015 versions seem fairly inexpensive (as of today anyway):
Hoover's Handbook of American Business 2015
Hoover's Handbook of World Business 2015
Hoover's Handbook of Emerging Companies 2015
Hoover's Handbook of Private Companies 2015