A common question people ask are what are the biggest private equity firms? People unfamiliar with the industry often misconstrue what the term “biggest” means. It can refer to assets under management (or AUM), number of investments, deal activity, size of deals or the number of employees at the firm.

I would say that the most common measure of the largest or biggest buyout firms is the assets under management or AUM. One measure of the size of a buyout firm is by the amount of private equity direct-investment capital raised by each firm over the past five years. By this measure we can find a list of the biggest buyout firms via Private Equity International magazine. P.E.I. 50 is a ranking of the largest PE firms using this measurement, here are the top ten of those fifty firms:

1. The Carlyle Group

2. Goldman Sachs Principal Investment Area

3. TPG

4. Kohlberg Kravis Roberts

5. CVC Capital Partners

6. Apollo Management

7. Bain Capital

8. Permira

9. Apax Partners

10. The Blackstone Group

This is not the complete picture of these firms however. For example, the size of a buyout firm does not mean that it is the best performing firm. Investors or professionals may be misled by the term “biggest” to interpret it to mean more than just the assets under management or capital that the firm has on hand to directly invest. You should also consider the performance of the firm, how many employees the firm has, its relative influence or control of a certain niche like energy companies or manufacturing firms, etc., and other indicators of the firm compared to other firms.