Abstract The new audit regulation came into force in Poland in 2017 and imposed mandatory audit rotation. The new regulation aims to strengthen the auditor’s independence but it might also affect concentration on the audit market. The aim of this paper was to analyse whether mandatory audit rotation has a potential to reduce the audit market concentration in Poland. The sample included 198 capital groups with the parent company listed on the Warsaw Stock Exchange. The own compilation was prepared based on the audit opinions which included information about appointed audit firms in the period 2011-2017 (1,386 observations in total). The paper includes the analysis of audit tenures, their length, frequency of changing the audit firm and direction of the changes (to Big-4 or to Non-Big-4). The results showed that the biggest capital groups tend to appoint Big-4 audit firms and if they change auditor—they choose another firm from the Big-4. Additionally, the high number of short-term tenures (up to five years) suggests that Big-4 firms have strong bargaining power and they benefit more from the rotation of the clients rather than from their retention. The findings significantly contribute to the hypothesis that mandatory audit rotation will not reduce the concentration on the audit market in Poland. The findings might be valuable for the regulators and supervisory authorities responsible for the monitoring of the concentration level on the audit market.

中文翻译：

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强制性审计轮换和审计市场集中度–来自波兰的证据

摘要新的审计法规于2017年在波兰生效，并对审计实行强制轮换。新规定旨在加强审计师的独立性，但也可能会影响审计师市场的集中度。本文的目的是分析强制性审计轮换是否有可能降低波兰的审计市场集中度。样本包括198个资本集团，母公司在华沙证券交易所上市。自己的汇编是基于审计意见而编写的，其中包括有关2011-2017年期间指定审计公司的信息（总计1,386项意见）。本文包括对审计任期的分析，审计任期的长短，更换审计公司的频率以及变更的方向（向Big-4或Non-Big-4变更）。结果表明，最大的资本集团倾向于任命Big-4审计公司，如果他们更换审计师，他们会从Big-4中选择另一家公司。此外，大量的短期任期（最多五年）表明，四大公司的议价能力很强，它们从客户的轮换而不是留住客户中受益更多。这些发现大大有助于以下假设：强制性审计轮换不会降低波兰审计市场的集中度。这些发现对于负责监督审计市场集中度的监管者和监管机构可能是有价值的。大量的短期任期（最多五年）表明，四大公司的议价能力很强，它们从客户的轮换而不是留住客户中受益更多。这些发现大大有助于以下假设：强制性审计轮换不会降低波兰审计市场的集中度。这些发现对于负责监督审计市场集中度的监管者和监管机构可能是有价值的。大量的短期任期（最多五年）表明，四大公司的议价能力很强，它们从客户的轮换而不是留住客户中受益更多。这些发现大大有助于以下假设：强制性审计轮换不会降低波兰审计市场的集中度。这些发现对于负责监督审计市场集中度的监管者和监管机构可能是有价值的。