The European Union's statutory audit market for large public-interest entities remains dominated by the 'Big Four' accounting firms—Deloitte, PwC, EY, and KPMG—despite regulatory efforts to increase competition. A 2023 study by the European Securities and Markets Authority (ESMA) found these firms audited approximately 85% of large listed companies in the EU, a concentration level that has seen little change over the past decade.
In response to this persistent market concentration, the EU's 2014 Audit Reform mandated mandatory firm rotation and prohibited certain non-audit services for audit clients. However, critics argue the reform has had limited success in breaking the oligopoly. Mid-tier networks like Mazars, BDO, and Grant Thornton have gained some market share but still audit a small fraction of major listed entities compared to the Big Four.
Recent discussions, including a 2025 European Commission consultation, have revisited the issue, focusing on whether additional measures like joint audits or stricter caps are needed. Proponents argue more competition is essential for audit quality and financial stability, while opponents caution against regulatory overreach that could disrupt capital markets. The debate continues as the EU evaluates the next steps for its audit framework.
