Do shareholders appreciate the audit committee and auditor moderation? Evidence from sustainability reporting

Purpose The purpose of this study is to investigate the association between sustainability reporting (SR) and firm value considering the moderating effect of audit committee (AC) quality and auditor tenure on this association. Design/methodology/approach The data for the study comprise 41,500 firm-year observations worldwide between 2007 and 2018 drawing on ten main sectors. The authors run a country-industry-year fixed effect regression and address endogeneity concerns with further methodologies. Findings First, the authors find that SR is significantly and positively associated with both firm value and industry-adjusted firm value. Further tests revealed that the baseline findings hold for SR assurance and the Global Reporting Initiative framework as well. Second, the moderation analysis outlined the significant moderating role that the AC assumes. More specifically, AC independence and expertise were found to strengthen the value relevance of SR. Third, the market also appreciates the moderation of auditor tenure in SR. Practical implications Investors appreciate greater corporate transparency which means that sustainability reports are likely to reduce information asymmetry and thereby agency conflicts. In addition, the moderation analyses imply that shareholders consider AC quality while they attach value to corporate sustainability reports. Hence, the structure of the auditing function appears to perform an implicit assurance role in the value relevance of sustainability reports. In line with these implications, corporations can review and re-design their auditing function and decide whether or not they will attest to sustainability reports given that AC independence and expertise and auditor tenure predict this decision. Originality/value The study highlights the audit function’s growing role beyond financial reporting and suggests implications for ACs and auditors in ensuring shareholders about the credibility of SR.