What had me reflecting on numbers was an article in the Financial Times (Conduit of Contention if you can find it) that talked about the Depository Trust and Clearing Corporation, which settles all the equity trades on American exchanges. According to the article the DTC settled 1.48 quadrillion dollars in transactions last year, the equivalent of the US GDP every three days.
I can’t even picture that much money!
It sounds like fun to manage that kind of volume in the abstract. In practice, maybe not so much fun. I would assume a very risk averse approach to change, and the results of a mistake could be astounding.
Tom Clancy included a programmer that put in code to destroy the data of the DTC in one of his novels, Debt of Honor. All transactions lost for a period of days. Total chaos. The fix? Pretend the transactions never occurred. There was no way to prove they did, so the fix was to just treat those ‘bad days’ as the equivalent of a bad dream. A strategy that still gets used in business occasionally!