Many database compilers these days build files and lists from any number of public company filings. We have seen company prospect files with no private company prospects. There will be private companies in the database but they are usually clients.
It is easy to find public companies. It is easy to find private companies in the US with the annual Forbes private list. However getting at private company data/estimates around the world is more difficult as the private companies are (in fact) private and not anxious to post figures.
In The Global 5000 database of the largest companies in the world, we currently have over 700 private companies with 600+ of those recently updated. The largest private companies include:
- Cargill – over $110 billion
- Glencore (in the process of filing an IPO)
- Koch Industries
- REWE of Germany
- US Postal Service (quasi government)
- Group Auchan
- Kaiser Permanente
- Reliance Group of India (some operations are public)
- Spar International
- Lloyds Insurance
- TNK Russia
- Lotte Holdings