[Code of Federal Regulations] [Title 31, Volume 2] [Revised as of July 1, 2006] From the U.S. Government Printing Office via GPO Access [CITE: 31CFR363.210] [Page 503] TITLE 31--MONEY AND FINANCE: TREASURY CHAPTER II--FISCAL SERVICE, DEPARTMENT OF THE TREASURY PART 363_REGULATIONS GOVERNING SECURITIES HELD IN TREASURYDIRECT--Table of Contents Subpart F_Marketable Treasury Securities Sec. 363.210 Is there any period of time during which I will be unable to process certain transactions regarding my security? A closed book period will be in effect for four business days prior to the date a marketable security interest or redemption payment is made. This means that certain transactions made during the closed book period will be delayed until after the closed book period is completed and the payment is made. You will be unable to transfer the security, change the payment destination, change the registration of the security, or use Treasury's Sell Direct[supreg] service during this closed book period.