| I don't have a good general answer; it's complex. But some specific things relevant to this story: Market makers are allowed and expected to run naked shorts in order to ensure liquidity. We want a system where you can just buy or sell an item "into the market", and then everything will get sorted out eventually. We optimise for the case where shares can be found because it's overwhelmingly common. Stock borrowing is routine and transparent. People often have no idea if their stock has been lent out or if they own a borrowed stock; the reason for this is because the system has been designed so it doesn't matter. Shorting is common and accepted. The volume of transactions is enormous, and the system began to freeze up under the weight of its own paperwork in the 60s and 70s. To work around this, a policy of stock immobilization was implemented to ensure that stocks don't need to physically change hands. As a result, almost all stocks in the US are actually owned by a small, obscure partnership called Cede & Co. As the excellent writer Matt Levine wrote a while back: > Nobody owns stock. What you own is an entitlement to stock held for you by your broker. But your broker doesn't own the stock either. What your broker owns is an entitlement to stock held for it by Cede & Co., which is a nominee of the Depository Trust Company, which is a company that is in the business of owning everyone's stock for them. This system sounds convoluted but actually makes it easy to keep track of things: If I sell stock to you, I don't have to courier over a paper share certificate, or call up the company and have it change its shareholder register. Our brokers just change some electronic entries at their DTC accounts and everything is cool. Dematerialization has been extremely helpful, but at scale, it moves us even further away from a system that deals with concrete items. Hence, eg, Levine's hilarious story "Banks Forgot Who Was Supposed to Own Dell Shares", from which my earlier excert comes from: https://www.bloomberg.com/opinion/articles/2015-07-14/banks-... Or for another even more hilarious story (also by Levine), "Dole Food Had Too Many Shares": https://www.bloomberg.com/opinion/articles/2017-02-17/dole-f... And so forth, and so on. The system, at every level, is not one where it makes any real sense to say "the company has issued five hundred thousand shares, I own twenty of them, I keep them in a drawer in my office, look, here are the serial numbers". It's more probabilistic than that, very much by design. |