The four major accounting firms refer to Deloitte, PricewaterhouseCoopers (PwC), KPMG and Ernst %26 Young. These firms are the four largest professional services firms in the world that provide auditing, transaction advisory, tax, consulting, risk and actuarial services. The Big Four conduct audits on most public and private companies around the world. The Big Four is the nickname used to refer to the four largest accounting firms in the United States, according to revenue.
These are Deloitte, Ernst %26 Young (EY), PricewaterhouseCoopers (PwC) and Klynveld Peat Marwick Goerdeler (KPMG). In addition to auditing services, the Big Four offers tax, strategic and management advisory services, valuation, market research, insurance and legal advice.