Regulating Sustainability Reporting in Europe: De Jure Harmonisation or De Facto Standardisation?

The paper aims to contribute to the debate about sustainability reporting through an evidence-based analysis of the contribution of the Global Reporting Initiative (GRI) to the standardisation of the non-financial disclosures prepared by the Italian public interest entities (PIEs). For the purpose of this study, we considered a sample of Italian PIEs affected by the effects of the Directive 2014/95/EU during the period 2017-2020. Following previous studies about financial accounting harmonisation, the analysis was built using the Herfindahl index (H-Index) and Comparability index (C-Index). The analysis reveals that the GRI standards contributed to achieving a higher degree of harmonisation. Furthermore, the analysis underlines an isomorphic approach related to the disclosure of non-financial information on a mandatory basis. Despite common legal requirements, we found virtuous companies voluntarily adopted a more sophisticated reporting approach to signal their orientation to sustainable and ethical paradigms.