The paper examines the impact of the institutional context and the regulation on the disclosure of non-GAAP indicators (NGIs), with a focus on the adoption of NGIs for opportunistic purposes. We firstly discuss the concept of opportunism and the approaches to discover opportunistic behaviours in the adjustment process. Then, we define a new procedure in three steps to highlight opportunistic behaviours. Based on a sample of 120 international listed companies, from 23 countries included in the S&P Global Oil Index, we employ logistic panel regression models to test our hypotheses about the role of the institutional context in affecting opportunism. First results suggest that while strong institutional contexts (developed market, high-quality legal system, protection for minority shareholders, common law system) reduce the disclosure of NGIs, they increase opportunistic behaviours. Moreover, the introduction of a regulation on NGIs increases the general disclosure of adjusted measures, but it does not moderate the opportunistic use of NGIs. Our research contributes to the non- GAAP literature providing a practical approach for measuring opportunism in NGIs disclosure. At the same time, the results provide useful insights to regulators and standard setters about the role and the effectiveness of regulations on NGIs in different institutional contexts.
Key-Words: Bilancio e comunicazione finanziaria