Modern financial systems rely on robust infrastructures to support efficient and resilient markets. Trading venues, clearinghouses, securities depositories, and trade repositories are the building blocks of the financial market architecture. Financial market infrastructures (FMIs) have been central in the post-crisis reform of global and domestic financial markets, with lawmakers closely regulating FMIs in the aftermath of the financial crisis. This book systematically analyses the current regulatory landscape of FMIs, specifically in the areas of trading and post-trading services in financial instruments. The legal regime for FMIs is complex due to the many relevant regulations and implementing measures. The comprehensive and cross-border approach of this book, covering both the EU and the US regimes, supports lawyers in understanding the law relevant to each step of a securities and financial transaction. The dual perspective taken in the book, covering both transactional and institutional aspects, deepens that understanding further. The volume is organized in three main parts introduced by a general discussion on the economic and legal evolution of FMIs. Parts I and II address trading and post-trading infrastructures and services in the securities and derivatives markets. Part III explains contemporary issues and challenges observable across a wide range of activities in both trading and post-trading services. Financial Market Infrastructures fills a void in the literature on FMIs, providing a comprehensive source of reference to the legal and regulatory framework. Trading venues and post-trading services in financial instruments are critical for the modern financial markets, and their economic and systemic relevance is fully analysed in this new work creating a valuable reference source for legal practitioners and scholars working in financial regulation.