Yoonseok Zang

Audit Market Concentration and Audit Quality

Policymakers and regulators have been concerned about the impact of audit market concentration resulting from decline in the number of audit firms due to mergers and the demise of Arthur Andersen. In this paper we find a positive association between audit market concentration (Herfindahl index) at the MSA level and audit quality (measured by discretionary accruals and the Dechow-Dichev (2002) measure of accrual quality). We control for fixed year effects, therefore our results are unlikely to be affected by the increase in concentration due to Andersen’s demise contemporaneous with an increase in audit quality because of regulatory measures such as SOX. Our results are robust to alternative concentration and audit quality measures, and several sensitivity tests attempting to rule out omitted variables correlated with client firms’ MSA location or attributes of clients and auditors. Our results are also robust to controls for endogeneity between audit market concentration and audit quality. Our evidence therefore supports the Government Accountability Office (2003, 2008) conclusions that increased audit market concentration is not currently a cause for concern.

Tax Aggressiveness and Auditor Resignation

We examine the relation between client tax aggressiveness and auditor’s resignation decision. Consistent with the agency view of tax avoidance which suggests that client tax aggressiveness can increase litigation and reputational risk to auditors and increase the potential conflict with managers, we find a positive association between our proxies for tax aggressiveness and the likelihood that an auditor resigns from an audit engagement. Further, this association is stronger when external monitoring of the client firm is less effective, when there is greater potential for agency problems in the client firm, and when the economic importance of the fees received from the client firm is lower. Overall, our study identifies client tax risk as an important determinant of auditors’ resignation. This result should be of interest to auditors who actively manage client audit risks and to tax authorities who have incentives to identify firms with abusive tax reporting behavior.