The Straits Times Index (STI), which tracks the 30 largest companies on the Singapore Exchange, currently features a uniform landscape when it comes to financial oversight. Every single constituent company in the index is audited by one of the Big Four firms: PwC, KPMG, EY, or Deloitte. Despite the presence of capable mid-sized audit firms in Singapore, such as Baker Tilly, BDO, and RSM, none have managed to secure an audit mandate among these blue-chip entities. This concentration of power highlights a significant barrier to entry for smaller firms, even those that successfully compete for initial public offerings and other corporate work.
In the 2025 financial year, the distribution of these mandates was led by KPMG with 13 clients, followed by PwC with 11, Deloitte with four, and EY with two. While the number of mandates is one metric, the financial scale is even more telling. PwC dominated the fee pool, accounting for 53.7 per cent of the S$151.1 million in total audit fees disclosed by STI companies. This concentration is further amplified by the fact that the five largest audit bills—paid by major institutions like Jardine Matheson, OCBC, Wilmar International, DBS, and UOB—accounted for nearly half of the total expenditure.
Industry observers note that this dominance is not necessarily driving up costs, but it does raise questions about market diversity and the resilience of the audit ecosystem. For the companies themselves, the choice of a Big Four auditor is often seen as a standard requirement for maintaining investor confidence and meeting the complex needs of large, multinational operations. As the Singapore Exchange continues its efforts to revitalize the equity market, the role of auditors remains a critical component of corporate governance and transparency.
Looking ahead, the primary uncertainty remains whether mid-tier firms can ever bridge the gap to audit the largest listed companies. While there is no immediate regulatory shift forcing a change, the ongoing discussion about audit quality and market competition suggests that the current structure will continue to be scrutinized by investors and regulators alike. For the public and shareholders, the key takeaway is that the audit market for Singapore’s top-tier companies remains a closed circle, defined by the scale and global reach of the Big Four.