It is interesting to note that for most of the 20 th century, there were actually eight accountancy firm which exert international dominance namely:-
- Arthur Andersen
- Arthur Young & Company
- Coopers & Lybrand
- Ernst & Whinney (until 1979 Ernst & Ernst in the US and Whinney Murray in the UK)
- Deloitte Haskins & Sells (until 1978 Haskins & Sells in the US and Deloitte Plender Griffiths in the UK)
- Peat Marwick Mitchell, later Peat Marwick
- Price Waterhouse
- Touche Ross
Competition among these public accountancy firms intensified and the Big 8 became the Big 6 in 1989 when Ernst & Whinney merged with Arthur Young to form Ernst & Young in June, and Deloitte, Haskins & Sells merged with Touche Ross to form Deloitte & Touche in August.
The Big 6 became the Big 5 in July 1998 when Price Waterhouse merged with Coopers & Lybrand to form PricewaterhouseCoopers.