The determinants of audit fees in the alternative investment market (Aim) in the UK: Evidence on the impact of risk, corporate governance and auditor size

This study examines the determinants of audit fees for companies listed on the Alternative Investment Market (AIM) in the United Kingdom (UK), which is the secondary market of the London Stock Exchange for small and medium sized companies. AIM companies are expected to present different audit pricing challenges compared to fully listed firms. From an audit demand perspective, AIM companies exhibit different risk and governance characteristics while, from a supply perspective, the AIM is characterized by greater auditor choice than typically found in main markets. We find that audit fees in the AIM are negatively influenced by client liquidity and the length of listing. We also find that higher levels of audit committee disclosures are associated with higher fees, although there is no evidence that individual audit committee characteristics influence audit fees. After controlling for self-selection bias, we find that Big 4 auditors charge higher fees and this premium is especially pronounced for smaller firms. Our findings contribute to the audit pricing literature by illustrating that the determinants of audit fees depends on the institutional setting in which companies operate as well as highlighting the importance of specific risk measures and auditor size in the determination of audit fees for AIM companies.