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Big Four accounting firms explained: A deep dive into the giants of accounting and consulting

Get insights into the Big Four companies in the world. Know their services, revenues, and how they help so many businesses with advice

By Forbes India

Published: Jun 10, 2025 05:05:36 PM IST

Updated: Jun 10, 2025 05:08:39 PM IST

Regardless of its success, every major company needs help making tough decisions. With constant market shifts and changing regulations, business strategies often need a different approach - this is where leading accounting firms and consultants come into the picture. From advising founders and executives on billion-dollar moves to helping startups stay compliant, these firms play a major role in keeping businesses running smoothly.

Some of these consulting firms have grown so influential that they’ve become trusted advisors to governments, Fortune 500 companies, and top financial institutions. They’ve built reputations over decades, and today, they dominate the global professional services space.

In this post, let’s discuss the Big Four companies in the world, what they do, and why so many businesses rely on them.

What is a Big Four company?

The Big Four refers to the four biggest consulting firms in the accounting and professional services space: Deloitte, PwC, EY, and KPMG. These are the leading accounting firms that handle the financial audits of most publicly listed companies, provide tax advice in corporate decisions, and consult with businesses on a range of topics, from strategy to digital transformation. Their presence is hard to miss across industries and countries.

Over the years, eight companies have merged to form the leading accounting firms. Arthur Young merged with Ernst & Whinney (Ernst and Young), Deloitte with Touche Ross, Price Waterhouse with Coopers & Lybrand (PwC), and one collapsed (Arthur Andersen) after the Enron scandal. That’s how the Big Eight became the Big Four.

These four companies set the pace for much of the financial and consulting world today.

What services do they offer?

The Big Four companies offer multiple professional services across various industries, including AI, supply chain management, sustainability, and more.

Here’s what they offer:

Audit and assurance: The leading accountancy firms review financial statements to confirm whether they’re accurate and meet legal standards. For example, Deloitte audits top companies like Adobe, Dell, and Yamaha.

Tax advisory: From corporate tax planning to international tax law guidance, the Big Four companies support organisations in staying compliant and optimising tax positions. For example, PwC partnered with Amazon, Google, and even OpenAI to help them grow and succeed.

Consulting services: These firms focus on business strategy, tech integration, operations, and human capital management across industries. For example, EY has consulted for P&G and Microsoft for risk management and supply chain operations.

Compliance and legal advisory: The Big Four companies support clients and help them navigate changing rules and policies across various jurisdictions. For example, KPMG has helped many engineering firms and HP with legal and tax matters.

List of the Big Four companies in the world

The Big Four companies in the world are ranked based on their revenue (in 2024), and here are the details:

S.no.	Big Four company	Revenue (in $ billion)	Key services offered
1	Deloitte	$67.2	Audit, business process solutions, enterprise performance, and risk management.
2	PricewaterhouseCoopers (PwC)	$55.4	Audit and assurance, business model reinvention, crisis management, and international tax services.
3	Ernst & Young (EY)	$51.2	Customer experience, cybersecurity consultation, financial accounting, and digital law.
4	Klynveld Peat Marwick Goerdeler (KPMG)	$38.4	Data analytics, tax management consulting, anti-money laundering compliance, and risk consultancy

A detailed insight into the Big Four Companies

The Big Four companies—Deloitte, PwC, EY, and KPMG—are the go-to consulting firms for global businesses. Their branches in India support major corporations, startups, and government bodies.

Deloitte

Deloitte ranked top in FY2024 with global revenues reaching $67.2 billion, marking a 3.6 percent growth from FY2023. With a global workforce of around 4.6 lakhs, Deloitte is renowned in India. This leading accounting firm has delivered 700+ GenAI projects across eight countries through its global GenAI incubator network. Deloitte was also named a leader in the 2024 Gartner and Verdantix reports for its role in finance and accounting business process outsourcing and sustainability measures.

PwC

PwC reported global revenues of $55.4 billion for the year ending June 2024, growing by 4.3 percent from 2023. Despite facing challenges in the Asia-Pacific region, PwC's business in India performed well, contributing to the firm's overall growth. The firm expanded its global workforce to 3.7 lakh employees and also invested $1.5 billion in AI capabilities.

EY

With revenue of $51.2 billion in FY2024, EY reported a nearly 4 percent growth compared to 2023. EY has deployed its core tech platform—EY Fabric—across 180 countries with over 2 million users. It launched EY.ai and EYQ, a secure, private large language model (LLM) that trains 70 percent of its workforce in responsible AI use. EY remains a key player in consulting and advisory services in India, supporting clients across various sectors.

KPMG

In 2024, KPMG's global revenues rose to $38.4 billion—a 5.4 percent growth from 2023. The consulting firm's growth in the Middle East, South Asia, Caucasus and Central Asia (MESAC) was robust, with a 19 percent increase in aggregated revenue across tax, audit, and advisory services. KPMG in India continues to provide services to a wide range of clients, strengthening its capabilities through senior hires across AI, cybersecurity, sustainability, risk and compliance, and taxation.