The riskiness of audit firm continuing clients' portfolio

Purpose – The purpose of this paper is to test whether firms audited by the same Big 4 audit firm (Big 4 continuing clients) are more/less likely to report material weaknesses (systemic material weaknesses) in internal controls over a financial reporting than those audited by the same Non‐Big 4 audit firm (Non‐Big 4 continuing clients) over the period 2005‐2008. It also investigates whether the number of material weaknesses and that of systemic material weaknesses varies among the two groups. Design/methodology/approach – Logistic regression and count regression analysis for panel data tests the hypotheses using all firms that had SOX 404 filings and that were audited by the same auditor over the period 2005‐2008 (1,668 firms; 6,672 firm‐year observations). Findings – Findings document that Big 4 continuing clients are less likely to report material weaknesses and systemic material weaknesses than Non‐Big 4 continuing clients, especially during the first two years of investigation. Results also demonstrate that the number of material weaknesses and that of systemic material weaknesses reported by Big 4 continuing clients is significantly lower than that reported by Non‐Big 4 continuing clients, primarily for the years 2005 and 2006. Originality/value – Findings support the risk avoidance perspective where large audit firms avoid riskier clients due to potential litigation costs and/or due to potential sanctions by the Public Company Accounting Oversight Board (PCAOB). Results also suggest that smaller audit firms did not extensively test the quality of internal controls prior to the year 2004. They highlight that the enactment of SOX 404 and the establishment of the PCAOB heightened audit firms focus on internal controls and raised their sensitivity to audit risk arising from weaknesses in internal controls over financial reporting.