Depository Trust Company (DTC), founded in 1973, is a New York corporation that performs the functions of a central securities depository as part of the US National Market System. DTC annually settles transactions worth hundreds of trillions of dollars, processes hundreds of millions of book-entry deliveries, and custodies millions of securities issues worth tens of trillions of dollars issued in the United States and over 100 other countries. Since 1999 it has been a subsidiary of the Depository Trust & Clearing Corporation, a securities holding company.