Since Regulation ATS was adopted in 1998, Alternative Trading Systems (ATSs), and in particular dark pools, have operated with a stunning degree of opacity, leaving market participants and regulators without basic, critical information about how these venues operate. The Security and Exchange Commission's proposed rule requirements for NMS Stock ATSs to disclose detailed information about their operations and potential conflicts of interest is long overdue, and CFA supports it as a necessary first step toward ensuring that these venues operate with integrity and accountability, that market participants can make more informed routing decisions, and that regulators have sufficient information to detect and deter wrongdoing. However, it is only a first step. Much more must be done, in this proposal and in future rulemakings, to fully protect investors in our modern market structure