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.
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.
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.
First Published: Jun 10, 2025, 17:05
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