Centering on a case study, this Article discusses the legal aspects of “net-short debt investing” on global bond markets through the lens of transnational fiduciary law. The aim of the Article is twofold. On the one hand, it is a comparative study on the potential and limitations of fiduciary law in a “hard case.” This analysis is inductive in nature. It aims at contributing to a better understanding of fiduciary law doctrines in both common and civil law jurisdictions. On the other hand, the Article focuses on the specific challenges of fiduciary law in transnational settings. In particular, it analyses the influence of transnational private ordering on the establishment of fiduciary duties in state law. The Article makes the case that the concept of fiduciary duties should be interpreted with a view to facilitating mechanisms of private ordering.