Back in ye olden days, if you wanted to buy stock for a specific price, you had to find someone who wanted to sell that stock to you for that price. So you’d have a guy on the floor of the stock exchange who you’d call up and say something like “I want to buy 10 shares of GM stock if you can get it for $10 a share”, and he’d try to find another broker who had a client who had called in wanting to sell.
These days, that’s all done on computers of course and the floor of the stock exchange is mostly a TV set.
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