They are the four largest accounting networks in the world measured by revenue. The Big Four is the nickname of the four largest accounting firms in the United States, measured by revenue. These are Deloitte, Ernst %26 Young (EY), PricewaterhouseCoopers (PwC) and Klynveld Peat Marwick Goerdeler (KPMG). PwC is the largest company in terms of revenue and the most prestigious of the four major companies, with a strong and consolidated base of auditing clients.
The Big 4 are the four largest international professional services and accounting firms. They are Deloitte, EY, KPMG and PwC. Each of them offers auditing, tax, consulting and financial advisory services to major companies.