Deloitte, EY, KPMG, and PwC make up the Big 4 — here's how they compare

• The Big Four — EY, Deloitte, KPMG, and PwC — are the world's largest accounting and consulting firms.

• They pull in billions annually but have faced a slowdown in demand for their services.

• This is how the Big Four have performed in recent years, and how they're looking to adapt in future.

Deloitte, EY, KPMG, and PwC are the world's largest accounting and consulting firms, known as the Big Four.

With histories dating back to the 19th century, they have grown into billion-dollar companies employing hundreds of thousands of staff who earn high salaries and often work very long hours.

The Big Four offer companies services such as workforce transformations, reshaping corporate finance portfolios, assurance, valuation, and optimizing the use of technology.

Put simply, they're there to assess businesses and tell them how to run more efficiently.

The pandemic changed the landscape for the major firms, with a surge in demand that sparked a hiring boom. The Big Four are now attempting to balance operations amid slowing demand.

Here's a look at where the Big Four stand.

After a series of mergers, EY was formed in 1989 as the accountancy firm Ernst & Young. It has since diversified its offerings and, in 2013, rebranded to EY.

Headquartered in central London, EY has more than 700 offices in 150 countries. Janet Truncale, the global chair and CEO, took over from Carmine Di Sibio in July.

EY focuses heavily on consultancy and assurance but also covers tax and strategy, and transactions.

Revenue was up 3.9% on the previous year to $51.2 billion, according to the firm's latest annual report published in October. It was EY's poorest performance since 2010. Assurance services were its largest revenue generator.

In May 2024, the firm was caught up in a scandal along with PwC and fined $11.7 million by UK authorities for a series of auditing failures.

As pressure has mounted, EY cut UK partner payouts by 5% and laid off employees. Overall employee numbers dropped by 2,450 during EY's latest financial year — the first decrease in 14 years.

EY's global head count now stands at about 393,000.

In 2023, the firm launched EY.ai, an AI platform aiming to assist clients across all its professional services. It also offers clients a conversational AI assistant called EYQ.

Deloitte is the largest of the Big Four by both revenue and employees.

Founded in the UK in 1845, Deloitte expanded into the US in 1890. It is headquartered in London and has more than 700 offices in some 150 countries. It's known for strong business and technology consulting services.