The Financial Industry Regulatory Authority (FINRA) expanded its oversight of alternative trading systems (ATS) yesterday, publishing block-size trade data occurring on nonpublic exchanges, like "dark pools,” The Hill reported today. The initiative to publish block-size trading statistics is the next chapter in FINRA’s initiative to shed light on ATS activity. FINRA started publishing volume and trade count data on equity securities executed in dark pools in June 2014, before making all over-the-counter volume transparent last April. Dark pools were initially created to house large trades without the level of information leakage associated with public exchanges. With the introduction of high-frequency trading, dark pools began to accommodate smaller trades. The new measure, published on a monthly basis, will allow the public to discern between firms that are still engaged in the traditional, large-scale trading and those hosting more small, high-frequency executions.
