[...] As volume and profits grew, more Wall Street partnerships were created to get in on the game. By the 1960s, electronic message switchboards replaced those pneumatic tubes of 1918 so order entry and execution confirmation could happen in something close to real time. Of course, this was to the advantage of the traders -- to be able to get the most current feel for the market; customers were still out of that loop. But the back office was neglected, stock certificates still had to be collected and distributed. Wall Street hit a wall in 1968, and for many it was fatal. Electronics facilitated trading but did nothing to help clearing and making sure buyers got certificates from the sellers.
As volume increased, by some 30% a year in both 1967 and 1968, the people-intensive clearing process took forever. Certificates piled up to the ceiling tiles at brokerage firms, either awaiting payment or as errors and bad trades yet to be reconciled. Hiring more people barely helped. Firms would work 24 hours a day, 7 days a week and still fall behind. Customers simply stopped paying since they stopped getting their certificates. The NYSE began closing one day a week to catch up. They mandated a Central Certificate Service that created electronic certificates for a few stocks so settlement and clearing could happen without handling physical certificates. It was too little, too late. 160 NYSE member firms went belly up in 1969 and 1970, their credit squeezed as it took so long to process the volume of trades, victims of their own success. It was a big problem for those not tech savvy.