Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Do market shares exhaust?
Let's clarify some things. Companies allow for the public to purchase their shares through Initial Public Offering (IPO) (first-time) and Seasoned Public Offering (SPO) (all other times). They choose however many shares they want to issue depending on the amount of capital they want to raise. What this means is that the current owners give up some ownership % in exchange for cash (usually). In the course of IPOs and SPOs, it can happen that the public will not buy all shares if there is very little interest, but I would assume that the more probable scenario if very little interest is present is that the shares' value would take a big drop on their issuance date from the proposed IPO/SPO price. After those shares are bought by the public, they are traded on Exchanges which are a secondary and (mostly) do not affect the underlying company. The shares are exchanged from John Doe to Jane Doe as John Doe believes the market value for those shares will take a direction that Jane Doe believes in the opposite. Generally speaking, markets will find an equilibrium price where you can reasonably easily buy-sell securities as the price is not too far from what most participants in the market believe it should be. In cases where all participants agree on the direction (most often in case of a crash) it can be hard to find a party to make a trade with. Say a company just announced negative news with long-lasting effects on the business there will be a surge in sell orders with very few buyers. If you are willing to buy, you will likely very easily find a trading partner but if you are trying to sell instead then you will have to compete for the lowest price against all other sellers. All that to say that in such cases, while shares are technically sellable / purchasable, the end result can be that no shares are purchasable.