When researching a company it is helpful to begin by determining whether the company is public, private, or a subsidiary of a larger parent company. This will give you a sense of where to look for information and what you might expect to find. To determine a company's status, find the company's profile using the resources within the Company Profiles & History section. Learn more about the various types of companies and the resources for researching information below:
Public Companies
A company that has issued securities and trades on a stock exchange. These companies are regulated by the SEC and are required disclose financial statements and annual 10-k reports. As such, more information is available for public companies. Use any of the resources within this research guide to search for public company information.
Private Companies
A company that is privately owned and does not have shares that are traded in public exchanges. Private companies are more difficult to research because they are not required to meet the same filing requirements of public companies. To research a private company search for current news articles, magazine profiles, and within trade publications using the resources found within the Current News & Articles section. Keep in mind that the smaller the company the less information you'll be likely to find.
Subsidiaries
A company that is completely or partially owned and controlled by a parent company. It is best to research the parent company to find information regarding the subsidiary. First determine the parent company by using a resource such as Mergent Online or LexisNexis. Then follow the suggestions for researching public and private companies.
(from https://nmsu.libguides.com/companyandindustryresearch)