Recent Evidence on Market Quality -- Intra-Day Volatility: Friend or Foe? -- View from the Trading Desks -- View from an ECN -- Perspective of the Market Architects -- Does Best Execution Make Sense? -- Thoughts from a Former Regulator -- Volatility in U.S. and European Equity Markets: An Assessment of Market Quality."Market quality" is a complex, ambiguous term that means different things to different people. How should it be defined, measured, monitored, and improved? What is the evidence about the current state of our markets? How effective have recent innovations been? How can we better meet investor needs? These are some of the questions that we address in this book, along with a broad range of issues concerning equity market structure, regulation, and the quest for best execution. Throughout, particular attention is given to the perspective of front line participants on the buy-side and sell-side trading desks.