회계감사서비스를 제공하는 대형 회계법인의 수가 점점 감소함에 따라 회계감사시장은 소수의 회계법인이 시장의 대부분을 과점하고 있는 상황에 직면하고 있다. 이에 따라 규제기관이나 학계에서는 이러한 회계감사시장의 과점상태가 감사품질이나 감사보수에 미치는 영향에 대해 높은 관심을 보이고 있다. 본 연구에서는 공급자의 집중도를 나타내는 산업별 허핀달 지수(Herfindahl index)로 측정한 회계감사시장의 산업별 감사인 집중도와 감사품질(재량적 발생액의 절대값으로 측정) 및 감사보수 사이의 관계를 1994년부터 2012년까지의 국내시장의 자료를 이용하여 검증하였다. 실증분석 결과, 허핀달 지수가 높아질수록 감사품질이 저해되며 감사보수는 하락한다는 것이 발견되었다. 본 연구의 발견은 다양한 정책적 시사점을 가지고 있으므로 규제기관에도 도움이 될 것이며, 학계에도 많은 후속연구 주제들을 제공해 줄 것이다.
This study investigates the association between the industry-level auditor competition and audit quality and audit fees. The audit market has witnessed a continuous decrease of the number of large audit suppliers (i.e., audit firms). Regulators questioned whether the dominance of the audit market by a few large auditors reduces the level of competition in the audit market (Government Accountability Office 2003, 2008; European Commission 2010). Specifically, based on the economic theory on the competition, the regulators expressed a concern that a possible collusion among the dominant auditors would lead to a low quality of audit service while charging oligopolistic high fees. As a result, the regulators asked to academics to investigate the effect of auditor competition on audit markets. Government Accountability Office (2003, 2008) also looked into the issue but did not make any clear conclusion on the effect of auditor concentration on the audit quality and the audit fee. Following the request, a few recent studies investigate the issue using U.S. data. These studies uniformly use Herfindahl index in each industry at the local audit market to proxy for the level of concentration in the audit market. To measure the audit quality, they use different proxies. Specifically, Kallapur et al. (2010) document that Herfindahl index is negatively related to the magnitude of earnings management, suggesting higher audit quality for more concentrated audit markets. Similarly, Newton et al. (2013) report that Herfindahl index is negatively related to the frequency of financial statement restatements. However, surprisingly, Boone et al. (2012) report that firms in the audit market with high Herfindahl index are more likely to meet or beat earnings benchmarks, resulting in lower audit quality. Collectively, the findings in these studies are mixed at best. In contrast, the studies that examine the association between auditor concentration and audit fees generally reveal that Herfindahl indexis negatively related to audit fees, relieving the regulators’ concern that the lack of competition leads to oligopolistic dominance of audit market by a few large auditors who charge high audit fees to their clients. It seems that the dominance by a few large auditors allows them to enjoy the economy of scale, which leads to lower costs in providing audit services. This study uses Korean data and investigates the same issue. In the past two decades, there were structural changes in the Korean audit market similar to those in the U.S. audit market. However, given the regulatory concerns on this issue and the potential importance of the effect of audit market structure on the audit industry, it is surprising that none of prior studies investigate this issue in Korea. Therefore, this study intends to fill this gap. Our sample consists of listed companies in the Korean stock market with available variables from 1994 to 2012. Empirical findings are summarized as follows. First, we find that industryyear level Herfindahl index is positively related to the magnitude of discretionary accruals. This finding shows a sharp contrast to those in the U.S. studies, which document the negative relation between two variables. This different result suggests an importance of performing Korean audit market studies independently from the U.S. studies. Furthermore, we find that the positive relation between Herfindahl index and audit quality is more pronounced as the Korean audit market structure moved from Big 6 to Big 5/Big 4. Second, we find that the Herfindahl index is negatively related to the level of audit fees. This finding is consistent with those in the U.S. studies. We also find that the negative relation between Herfindahl index and audit fees did not change significantly as the market structure changed from Big 5 to Big 4. Our findings are subject to some caveats, including whether the Herfindahl index exactly represents the intensity of competition in the audit market. However, our findings are interesting because they provide several valuable insights to regulators, academics, investors, and the other interested parties. Given that almost no Korean studies investigate the incentives of auditors related to audit market structure, this study provides valuable intuitions. Especially, our findings suggest that the regulators need to consider weakening the dominant market structure of a few large auditors in order to improve the quality of audit service.