Did some research on Trade-for-Trade awhile back. It is not always a negative. Can be applied by the company that is close to announcing a significant event in order to limit manipulation, companies in the process of reorganization, getting a new cusip #, etc. See page 6 of this publication http://www.sifmasos.org/attachments/contentmanagers/72/SOD_NewsView%20spring%202007.pdf Also see http://www.dtcc.com/downloads/products/learning/Deposits.pdf Page 12 explains the CNS process Good luck!