The Big Four refers to the four largest global accounting firms—Deloitte, PwC, EY, and KPMG—that provide a range of services.
What Is the ‘Big Four’?
Measured by revenue, the Big Four global accounting firms are Deloitte, Ernst & Young (EY), PricewaterhouseCoopers (PwC), and Klynveld Peat Marwick Goerdeler (KPMG). The companies provide auditing services, tax, strategy and management consulting, valuation, market research, assurance, and legal advisory services. All four are leading sources of tax law interpretation and accounting and auditing standards.
Key Takeaways
- The “Big Four” refers to the four largest accounting firms in the United States.
- Four firms audit the financial statements of the majority of publicly held companies.
- The Big Four provide auditing, tax, consulting, valuation, market research, assurance, and legal advisory services.
1. Deloitte
The largest of the Big Four, Deloitte’s workforce grew to 460,000 employees during its 2024 fiscal year (FY). The company’s annual revenue was $67.2 billion. Deloitte operates in more than 150 countries.
2. PwC
In 2024, PwC reported an annual revenue of $55.4 billion, the second-highest amount for Big Four firms. PwC also added 6,161 more jobs during the year, boosting its workforce to more than 370,000 in 149 countries. The company made a $1.5 billion investment in artificial intelligence (AI) initiatives and debuted its ChatPwC platform.
3. EY
For FY 2024, Ernst & Young reported $51.2 billion of company-wide revenue. The company also celebrated the one-year anniversaries of its AI platform and its AI assistant with large language model (LLM) capable of conversing with users to assist with creating ideas and research. The firm employs more than 393,000 people and operates in more than 150 countries.
4. KPMG
In 2024, KPMG reported the equivalent of $38.4 billion of revenue with growth across all divisions. KPMG employs over 275,000 individuals globally, operates in 142 countries, and has an office in almost every U.S. state.
| 2024 Annual Revenue in U.S. Dollars | # of Employees | # of Countries of Operation/Headquarters | |
|---|---|---|---|
| Deloitte | $67.2 billion | 460,000 | 150+/London, U.K. |
| PwC | $55.4 billion | 370,000+ | 149/London, U.K. (global) and New York City, U.S. (U.S.) |
| EY | $51.2 billion | 393,025 | 150+/London, U.K. |
| KPMG | $38.4 billion | 275,000+ | 142/Amstelveen, Netherlands |
History of the Big Four
Through industry consolidation that began in 1989, what used to be the Big Eight is the Big Four in 2025. The original eight, based in the United States or the United Kingdom, were Arthur Andersen, Arthur Young, Coopers & Lybrand, Deloitte Haskin & Sells, Ernst & Whinney, Peat Marwick Mitchell, Price Waterhouse, and Touche Ross.
Arthur Young combined with Ernst & Whinney, while Deloitte Haskin & Sells merged with Touche Ross. Price Waterhouse and Coopers & Lybrand merged their practices. Following the collapse of Arthur Andersen, due to its proven culpability in the Enron scandal, the five became four. The Big Four perform most of the auditing work for some of the largest public companies.
The most recent data available shows the Big Four constituted 99.7% of the S&P 500 market in 2022 and 100% of the Fortune 500 in 2025, dominating the audit fee market share. PwC led S&P 500 market auditing with 35.7%, according to data compiled by Ideagen.
Important
In 2002, “Big Eight” firm Arthur Andersen was discovered to have shredded documentation in an effort to hide Enron’s falsified financial numbers. One of the largest and most reputable firms at the time, it ultimately collapsed due to the scandal.
Big Four Salaries
| Deloitte | PwC | EY | KPMG | |
| Tax Analyst | $88,884 | $86,030 | $46,762 | $94,808 |
| Accountant | $87,346 | $93,405 | $74,103 | $82,583 |
| Certified Public Accountant | $88,781 | $96,212 | $95,241 | $95,860 |
| Auditor | $85,213 | $81,554 | $77,273 | $77,047 |
| Business Analyst | $80,724 | $78,433 | $105,921 | $40,210 |
| Cybersecurity/IT Analyst | $87,582 | $80,467 | $57,914 (cybersecurity analyst); $67,990 (IT analyst) | $100,859 |
What Services Do the Big Four Companies Provide?
Big Four firms provide audit, assurance, consulting, financial advisory, risk management, and tax compliance services. Each firm also assists with mergers, acquisitions, corporate restructurings, and forensic accounting.
What Is Busy Season Like at a Big Four Company?
The busy season typically means long hours of auditing or tax compliance work to meet reporting deadlines. Big Four employees often work long hours during the busy season, sometimes doubling the hours worked during the offseason. The busy season typically begins at the start of the calendar year, with tax reports and returns due from January to April. Big Four firms are also busy during periods when companies report quarterly or yearly earnings.
What Is the Difference Between an Accountant and a CPA?
An accountant is a professional with a bachelor’s degree in accounting. A CPA, or Certified Public Accountant, is a professional who has earned a CPA license through education, experience, and examination.
The Bottom Line
The “Big Four” refers to the four largest accounting firms and comprises Deloitte, PwC, KPMG, and EY. All four companies provide audit, assurance, consulting, financial advisory, risk management, and tax compliance services.
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