CSDs hold securities, either in certificated or uncertificated (dematerialized) form, to enable the transfer of ownership of securities.
CSDs are not necessarily custodians, since they may be responsible only for registering and settling security transactions. The major U.S. central securities depository is Depository Trust and Clearing Corporation (DTCC) and the major foreign- resident central securities 31 depositories are Euroclear and Clearstream.