as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
do market shares exhaust?
user
as @applepie pointed out in their answer, at any given time there is a finite amount of stock available in a company. one subtlety you may be missing is that there is always a price associated with an offer to buy shares. that is, you don't put in an order simply to buy 1 share of abc, you put in an order to buy 1 share of abc for $10. if no one is willing to sell a share of abc for $10, then your order will go unfilled. this happens millions of times a day as traders try to figure the cheapest price they can get for a stock. practically speaking, there is always a price at which people are willing to sell their shares. you can put in a market order for 1 share of abc, which says essentially "i want one share of abc, and i will pay whatever the market deems to be the price". your broker will find you 1 share, but you may be very unhappy about the price you have to pay! while it's very rare for a market to have nobody willing to sell at any price, it occasionally happens that no one is willing to buy at any price. this causes a market crash, as in the 2007-2008 financial crisis, when suddenly everyone became very suspicious of how much debt the major banks actually held, and for a few days, very few traders were willing to buy bank stocks at any price.
assistant