The Big Four are the four largest global accounting and professional services firms: Deloitte, PwC, Ernst & Young, and KPMG. They dominate the global market for auditing, consulting, and tax advisory services, and they audit the majority of large multinational corporations.
These firms are highly influential because they operate across many countries, have deep relationships with major companies, and play a key role in ensuring the credibility of financial reporting in global markets.
However, the Big Four have faced increasing criticism in recent years due to audit failures, their inability to detect major corporate fraud, and concerns about conflicts of interest arising from providing both audit and consulting services to the same clients. They are also facing growing regulatory scrutiny and pressure to reform their structure and practices.