Explore which audit firms audit the world’s largest listed companies, how long they have held those engagements, and how much companies pay for audit services.
The audit of a major listed company is one of the most important gatekeeping functions in the capital markets.
Yet information about who audits which company, how long the auditor has been in place, and how much the engagement costs is often scattered across annual reports, regulatory filings and shareholder documents.
Big4News is bringing that information together.
Our Who Audits? project tracks the external auditors of major companies around the world, covering leading stock-market indices as well as other defined groups of major companies.
For details on how Big4News identifies auditors, establishes auditor tenure, records audit fees and handles incomplete or complex disclosures, see our Who Audits? Sources & Methodology page.
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The global audit market at a glance
The Big Four dominate the audit of the world’s largest listed companies, but the extent of that dominance varies significantly between markets.
In the United States, the Big Four audit 494 of the 500 companies in the S&P 500, leaving just six mandates to firms outside the four global networks. Japan is similarly concentrated: 218 of the 225 Nikkei 225 companies are audited by a Big Four firm.
Other markets provide more room for challengers. India has a sizeable group of domestic and mid-tier firms auditing Nifty 50 companies, while France is structurally different because its joint-audit regime means most CAC 40 companies appoint two statutory auditors. That has given Forvis Mazars a substantial presence alongside Deloitte, EY, KPMG and PwC.
Auditor tenure also differs sharply between jurisdictions. Some US and Japanese companies have audit relationships stretching back many decades, while mandatory firm-rotation rules in parts of Europe have resulted in considerably more recent appointments among major listed companies.
The individual market pages allow these differences to be explored company by company, together with analysis of Big Four market share, auditor tenure, audit fees and the regulatory features that shape each local audit market.
What the data includes
Who Audits? datasets typically identify:
Company — the company included in the relevant dataset.
Auditor — the external audit firm responsible for the statutory audit.
Since — the first financial year audited by the current audit firm, where this can be established reliably.
Audit fee — the latest publicly disclosed fee for audit services.
Big4News compiles the data primarily from annual reports, regulatory filings, auditor reports and other primary corporate disclosures. Where a data point cannot be established to a sufficiently high standard, it is left unresolved rather than estimated.
For full definitions, sourcing standards and details of how we treat auditor tenure, joint audits, currency conversion, firm changes and incomplete disclosures, see Who Audits? Sources & Methodology.
The objective is to provide a transparent reference point for understanding the structure of the global audit market: which firms dominate major markets and sectors, where auditor changes are taking place, how long major companies retain their auditors, and how audit fees differ across companies.
Big4News will continue expanding and updating the Who Audits? project as new annual reports, auditor appointments and financial disclosures become available.