This book examines the post-crisis international derivatives regulation by bringing together the international relations literature on regime complexity and the international political economy literature on financial regulation. Specifically, it addresses three interconnected questions. What factors drove international standard-setting on derivatives post-crisis? Why did international regime complexity emerge? How was it managed and with what outcomes? Theoretically, this research innovatively combines a state-centric, a transgovernmental and a business-led explanations. Empirically, it examines all the main sets of standards (or elemental regimes) concerning derivatives, namely: trading, clearing, and reporting derivatives; resilience, recovery, and resolution of central counterparties; bank capital requirements for bank exposures to central counterparties and derivatives; margins for derivatives non-centrally cleared. Regime complexity in derivatives ensued from the multi-dimensionality and the interlinkages of the problems to tackle, especially because it was a new policy area without a focal international standard-setter. Overall, the international cooperation that took place in order to promote regulatory precision, stringency, and consistency in the regime complex on derivatives was remarkable, especially considering the large number of policy actors involved (states, private actors, regulators). The main jurisdictions played an important role in managing regime complexity, but their effectiveness was constrained by limited domestic coordination. Networks of regulators facilitated international standard-setting and contributed to managing regime complexity through formal and informal tools. The financial industry, at times, lobbied in favour of less precise and stringent rules, engaging in international ‘venue shopping’; other times, it promoted regulatory harmonization and consistency.