These are likely to be the best online sources in which to start your research.
When researching a company, it is important to know whether the company is public (traded on the stock exchange), private, or a subsidiary or division of a larger company.
The U.S. Securities and Exchange Commission requires all public companies whose stock is traded on an American exchange (except foreign companies and companies with less than $10 million in assets and 500 shareholders) to file numerous reports electronically through the EDGAR database.
Unless they are publicly traded, subsidiaries and divisions of larger companies are not required to release annual reports or financial information. Sometimes this information can be found in the parent company's annual report.
It is important to balance information that companies release about themselves with information from other sources, such as information found in articles and newspaper reports (See the Library's List of Business and Economics Databases).