The book provides an analysis of the emergence, evolution, and transformation of transnational securities regulation and of the influences from and the interactions between global regulatory powers in the field. Combining insights from law and political science, the work employs a two-tier complementary "on-the-books" and "in-action” approach. The more classical "on-the-books" approach draws on scholarship in United States and European Union securities regulation; transnational regulation and global administrative law; regime complexity; global governance studies; and the regulatory production of the International Organisation of Securities Commissions (IOSCO). The law in-action approach leverages the author’s experience as Compliance senior professional in a multinational financial institution as well as research interviews with senior IOSCO staff. The author’s findings enable the reader to develop an original understanding of IOSCO, its standards, and its unique place in the transnational regulatory arena. They also challenge the doxa that the US are the only driving regulatory power in the securities area when in fact, other regulatory powers are emerging – for the time being, the EU. The balance has shifted and regulatory compromises are achieved at different points in the rule making process.