Effective July 11, 2011, FINRA will start a three-phase plan to track trades in all listed US stocks. Trades will be tracked using the Order Audit Trail System (OATS), which is currently used in recording and reporting trades on NASDAQ and in OTC equity securities. Relevant to Series 7, Series 24 and Series 62 exams.
http://www.finra.org/Industry/Regulation/Notices/2011/P122786