For a publicly traded company this information is often available in their regulatory reporting documents. In the United States this is their required SEC filings.
This information is very difficult to get for a private company. For a private company you will need to be a great detective. As such you will be souraging multiple sources of information and putting the picture together from a variety of puzzle pieces. These will include:
- Their website
- Press releases
- News reports
- Relative information based on other competitors for whom you have this information
- Social media profiles
- Parking spots at their offices
- Ex-employees looking for work
- Drunken conversations overheard at the Country Club
Have fun being a sluth-- and make sure that you are only spending the time that you really need to in order to stay focused on growing your company.