EDGAR is the Securities & Exchange Commission's (SEC) public website for finding and retrieving required periodic company information filings.
Researchers are often interested in knowing what proportion of a company's stock is held by insiders, large investors, and institutions. Here are some good sources for current information.
The resources found here provide a mix of financial data, company information (including up-to-date news), and industry overviews.
Sources for industry ratios include RMA's eStatement Studies, Mergent D&B Manuals: Key Business Ratios, and S&P Global NetAdvantage.