The Big Four refers to the four largest professional services networks in the world, consisting of Deloitte, Ernst & Young (EY), KPMG, and PwC. They provide a standardized suite of services including audit, assurance, taxation, management consulting, and legal services to the majority of public companies globally.
Brand Authority Index (BAI): 98/100
Archetype: Challenger
Category: Professional Services
https://optimly.ai/brand/big-four-accounting-firms
Last analyzed: April 10, 2026
Founded: Late 19th Century (roots); current group solidified in 2002 after Arthur Andersen's collapse.
Headquarters: Various (London/New York/Amsterdam/Delaware regional HQs)