This chapter explores the dual motivations that underlie the disclosure of non-GAAP performance indicators: the desire to inform better capital markets and the opportunity to mislead stakeholders. The debate between informativeness and opportunism is examined in depth, outlining the key arguments and supporting evidence in academic literature. Emphasis is placed on the role of managerial discretion and the potential for both transparency enhancement and misleading reporting. While references are made to an empirical study on the European market, the discussion remains exploratory, setting the stage for future, more detailed investigations. The chapter documents that the risk of misleading non-sophisticated investors remains significant. These considerations raise critical questions about how oversight mechanisms—analyzed later—can curb the misuse of non-GAAP metrics and enhance their reliability in financial markets.