Once known as the “Big Eight”, was reduced to the “Big Six” and then the “Big Five” by a series of mergers. The Big Five became the Big Four after the fall of Arthur Andersen in 2002, following its involvement in the Enron scandal.

Rank by revenue as of March, 1985:

1. Arthur Andersen
2. Peat, Marwick, Mitchell & Co.
3. Ernst & Whinney
4. Coopers & Lybrand
5. Price Waterhouse
6. Arthur Young & Co.
7. Deloitte, Haskins & Sells
8. Touche Ross

Other large professional services networks include BDO, RSM, Grant Thornton, Crowe Horwath, HLB and Clifton Larson Allen.