This book explores various regulatory, legal, and competitive pressures that the U.S. securities industry is facing as a result of the intense regulatory scrutiny of the modern electronic marketplace and the heated public debate stirred by Flash Boys by Michael Lewis. This collection of previously published and unpublished materials includes the following articles and white papers: 1. 20 Predictions for the Future of the Market Structure Crisis - provides an overview of the current market structure crisis and offers forecasts for regulatory, legal, and commercial developments 2. Deconstructing Maker-Taker - analyzes the nature and implications of the maker-taker pricing model and discusses its role in the current market structure 3. Reigniting the Order Type Debate - reviews recent order type-related rule submissions by securities exchange and discusses the nature of "undocumented" order type features and order matching engine practices 4. The Problem of Fragmentation and Potential Solutions - presents various issues related to the "dispersed" trading process, analyzes different order flow allocation mechanisms, such as maker-taker and payment for order flow arrangements, and reviews potential regulatory solutions 5. HFT Regulation and Market Structure Reform - discusses the emergence of HFT regulation, including various proposals concerning restraints on electronic trading, approaches to slowing down or mechanically restraining the trading process, and the elimination of certain shortcuts embedded in the current market structure 6. Leveling the Playing Field: Lit and Dark Trading Venues - reviews recent enforcement actions directed at trading venues, analyzes the doctrine of regulatory immunity, and addresses a variety of other issues relevant for trading venues 7. Protecting Customers and Achieving Best Execution: Issues for Retail and Institutional Brokers - analyzes various concerns relevant for retail and institutional brokers, including the evolving duty of best execution and its extension to other parties, maker-taker and payment for order flow arrangements, and special order types 8. Litigation and the Impact of Enforcement: The Market Structure Perspective - provides as overview of the litigation landscape for market structure-related issues, including private lawsuits directed at major trading venues and brokerage firms, and discusses the significance of enforcement actions 9. Public Comment Letter on Several Order Type-Related Modifications Proposed by the New York Stock Exchange - offers a critique of the proposed functionalities and discusses the phenomenon of post-only intermarket sweep orders 10. The Flash Boys Lawsuit: The End of the Beginning? - discusses the path of the City of Providence v. BATS class action lawsuit, which has been referred to as the "Flash Boys Lawsuit," and analyzes the prospects of private lawsuits in the market structure space Appendix A - Summary of Key Enforcement Actions and Lawsuits Appendix B - Selected Market Structure-Related References