The Commodity Futures Trading Commission will host a public meeting on November 4 to consider a supplemental proposal regarding Regulation Automated Trading initially issued in November 2015. Previously, Timothy Massad, CFTC Chairman, indicated that amendments to initially proposed Regulation AT would likely modify, but not eliminate, initial requirements related to registration, source code and who is obligated to maintain risk controls. (Click here for background in the article, “Registration Based on Quantitative Test Likely to Be Part of Supplemental Regulation AT, Suggests CFTC Chairman” in the October 23, 2016 edition of Bridging the Week.) Last week, during a conference on The Evolving Structure of the US Treasury Market, Mr. Massad indicated that one of the justifications for adding a volumetric test to assess who should be newly required to register as a so-called AT person is that often, “a small number of traders can represent a large percentage of total trading volume.” For example, he noted that during the recent collapse of the British Pound on October 6, 2016 during illiquid trading hours, the ten most active trading firms constituted 60 percent of all trading activity in the Chicago Mercantile Exchange’s British Pound futures contract. Separately, at the same conference, Mary Jo White, Chair of the Securities and Exchange Commission, suggested that there is “significant concern” that certain principal traders that effectively act as dealers in US Treasury securities are not currently required to register with the SEC. She also indicated that SEC staff is currently reviewing disruptive trading practices in the equities markets and will soon publish a report for public comment.