Item — HN Reader

Delay in settlements shouldn't matter in the case you described, and the specific problem you're describing is solved by using limit orders rather than market orders (of course, the order might not fill in that case but that's the risk you take with using limit orders).

The problem with real time for everyone is that the tech required to do that is complicated and it's not necessary for most people.

1 comments

its odd to me that the market can arbitrarily decide not to fill a sale at a listed price. I'm still not grasping why that is possible. You'd need to mathematically prove there was no buyer for the stock at X price not to fulfill the sale yes? Thats the only way it makes sense to me, yet I know thats not the case by just looking at the sell volume (there was, in fact, to the best of my knowledge, trades executing buy orders - though in my personal example, it was a few hours where the price was higher then went lower)

> its odd to me that the market can arbitrarily decide not to fill a sale at a listed price.

You might be misinterpreting what the "listed price" actually is on a stock market. Prices that you see quoted are generally not prices that somebody is offering to sell at; they are the price that the last sale was made at. But that sale has already executed, so you cannot infer that there is someone else still willing to sell at that price. The only way to find out for sure what is available at what price is to place a buy order, and your buy order is not guaranteed to execute immediately because there might not be a matching sell order in the order book; it is not even guaranteed to execute as soon as there is a single matching sell order in the order book. It depends on the type of order and the exchange it is placed on and how orders and trades are reconciled. It's not like going into a store and taking an item to the cashier and buying it at the advertised price.

You have your thinking backwards because you're ignoring the need for a counterparty. In order for your sale to happen the market must first find a buyer to match it with (otherwise how could you trade?). There's no need to mathematically prove there isn't some other buyer as the whole point is to match the two.

Limit orders at the same price are filled in FIFO order, and it can be the case that that some limit orders fill while others do not simply because someone was only willing to buy 100 shares at that price and there were 200 available for sale - some sales won't happen.