Big Four

Common usages

Typical applications of the label include business and finance, transportation history, and sport. These usages are independent of one another but share the idea of four leading participants. Examples frequently cited in English-language sources are:

• The four largest global accounting firms (commonly called the accounting Big Four).
• Groups of four dominant banks in a national market — see Big Four (banking) for one usage.
• The four major British railway companies formed in 1923 and operating until nationalisation after World War II.
• Informal quartets in sport, such as the men's tennis players often referred to as a "Big Four" in the 2000s and 2010s.

Accounting firms

When used without qualification in business media, "Big Four" most often denotes the four largest international professional services and auditing firms: Deloitte, PricewaterhouseCoopers (PwC), Ernst & Young (EY) and KPMG. These firms provide audit, tax, consulting and advisory services and have a sizable global footprint, which has prompted regulatory and public discussion about market concentration in auditing and professional services.

Banking and finance

In banking, "Big Four" can identify the four largest banks within a country or region by assets, market share, or regulatory significance. The specific banks differ from place to place and over time. Because of this variability, references to the banking "Big Four" typically appear with a geographic qualifier or are linked to a particular article or dataset.

British railway companies (1923–1947)

In the United Kingdom the phrase historically refers to the quartet of companies created by the Railways Act 1921 and operating from 1923 until nationalisation in 1948: Great Western Railway (GWR), London, Midland and Scottish Railway (LMS), London and North Eastern Railway (LNER) and Southern Railway (SR). They coordinated timetables and competed for passengers and freight while remaining separate corporate entities.

Other uses and notable points

Various cultural and sporting contexts adopt the "Big Four" label to describe a dominant set of four competitors, institutions or figures. Because the term is informal, it can change as markets, rankings or careers evolve. When citing a "Big Four" grouping, readers should check the geographic scope and time frame to understand exactly which four entities are meant.