Big Four The four largest public accounting firms in the U.S.: Deloitte, Ernst & Young, KPMG, PricewaterhouseCoopers. Typically, these four firms perform the audits of the largest publicly-traded corporations. In the UK, the four large clearing banks: Barclays, Midland, Lloyds and National Westminster. In Japan the largest securities houses: Daiwa, Nikko, Nomura and Yamaichi.

- Used to explain the concept in accounting and business contexts.
- Used when training staff or documenting procedures and policies.

- Example: Teams reference **BIG 4** when defining terms in manuals, policies, or training materials.

- Why it matters: Improves clarity and consistency across documentation and decision-making.