unofan
Well-known member
If someone on here can explain this to me, I will GrubHub you a steak dinner. I have never found anyone who can explain to me how stock prices are actually set, including my MBA finance professors. They only think at the micro level, on an individual trade basis. What are the macro effects of all the buy and sell orders that are going on? Some simple examples that would illuminate a lot, for me at least:
Example 1: Say price is $50. 5 people say that they want to sell their combined 500 shares. 8 people say that they want to buy a combined total of 400 shares. I presume that the 400 shares trade hands at $50, but there are now an excess of 100 shares that want to be sold. Does that mean that "they" would drop the price to try to attract buyers for those 100 shares? If so, how quickly does the price drop? Do they knock off 1% and wait 1 minute, then drop another 1%? Or is it .1% every 3 seconds?
Example 2: Price is $50. 5 sellers put in standing orders to sell 500 shares at any price over $49. I put in an order to buy 400 shares. I assume I get those shares at $50. Then what happens to the price? Would they drop the price to $49 due to the "excess" standing sell orders, but no lower?
Example 3: Say price is $50. 10 people put in standing orders on 500 shares saying that they'll sell at any price over $55. I put in an order that I want to buy 100 shares, thinking that I'm going to get it for $50. Would "they" raise the price to $55 (due to the "excess" buy demand from me) to make those 100 trades happen (but I pay a 10% higher price than I expected)?
Example 4: Same as example 2, but my buy order included a cap that said I was not willing to pay any more than $50. Would they still raise the price to $51 (even though no trades would happen) since there was a greater signal from investors that the price should go up (as evidenced by the greater number of sell orders at $55 than they have for buy orders at $50)?
Example 1 is easy - 400 shares trade hands at $50, and the price remains at $50 unless and until the next trade is made at a different price. It's up to the seller to either change his asking price, let it sit at $50 until someone buys, or if he's doing a market sell, wait until someone comes in with a buy order at a different price and sells them to him.
Example 2 is also easy - assuming your order to buy 400 shares was at the market price, you'd get them for $49 and set the new price, with the current ask still at $49.
Example 3 depends on your buy order - if you buy at the market price, you'd pay $55 because that's the current ask and set the new price.
Example 4 - no sale happens because the bid and the ask don't match, therefore the listed market price stays at $50 because that is still the last recorded sale. Someone else would need to come in or someone needs to flinch.
If you delve into the markets, you'll see the highest bids and lowest asks outstanding for a given stock. High frequency traders and the brokerages will make money off the spread by buying at the bid price and then hopefully reselling at the ask price over and over and over again (or vice versa, selling at the ask and then hopefully re-buying at the bid). So for retail investors like you or me trying to sell 100 shares of a stock, the brokerages will often simply handle that themselves by buying your 100 shares at the bid price and then turning around and selling them at or slightly lower than the latest ask price (or vice versa, they'll sell shares to you at the ask price and then rebuy them at the current bid price or slightly higher).
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