Wall Street's paperwork crisis and the Depository Trust Company (1973)
In the late 1960s, trading volume outran the clerks who physically moved stock certificates between firms. Backlogs of unprocessed trades grew so large that the New York Stock Exchange shortened its trading week to let the paperwork catch up. The Depository Trust Company opened in 1973 to hold certificates in one place and settle trades by book entry instead of delivery.
Firms stopped shipping paper certificates between offices for most trades.
Book-entry settlement became the default for US securities, and the depository became a piece of market infrastructure nobody thinks about until it fails.
Settlement layers get rebuilt when volume outgrows the manual step. Here the manual step is the interbank dollar leg, and the replacement is a token.
