Why is Big Four (PwC, Deloitte, E&Y and KPMG) not listed in the Fortune 500 every year?

It seems that there are potential answers (in order of likelihood):

Accenture is an LLP / partnership, not a corporation

It does not provide the information required to be listed

The US-based revenue (or other factors) technically doesnt meet the criteria for listing

What is the Fortune 500? How does a company make it to the Fortune 500 list?

Which Fortune 500 company has the fewest number of employees?

What is the Fortune 500? How does a company make it to the Fortune 500 list?

Which Fortune 500 company has the fewest number of employees?

What is the average annual salary at Fortune 500 companies?

Which Fortune 500 companies are more than 100 years old?

What is a Fortune 200 company? How are they different from Fortune 500 companies?

Why do Fortune 500 companies require so much management?

How many employees does each Fortune 500 company have?

What is the daily routine of CEOs of Fortune 500 companies?

What is the Fortune 500? How does a company make it to the Fortune 500 list?

Which Fortune 500 company has the fewest number of employees?

What is the average annual salary at Fortune 500 companies?