A question i have been wondering for a while, imagine me and 10 people is selling at ABC stock at rm 1, and my bro decided to buy the share. How do the program decide whose share out of the 10 people does he buy?

First in First Out

So its like a queue list la

Order matching rules according to priority:
1) Price precedence: Best bid/ask.
2) Display precedence: Display over hidden at same price.
3) Time precedence: First over others with same price and display properties.

This means order will be matched first according to best price followed by "display" then "hidden" orders. Lastly, time.

Sorry to ask but what is hidden and display order? is it something similar to limit order?

It's just a characteristic of an order. Limit order can be hidden or display or partly hidden and partly display.

Hidden means it's not seen by everyone but it's there. Display means it's seen by everyone.

I believe Malaysia retail investors (people like us) don't have access to hidden orders so you don't have to know.



Example of Display order in AmEquities. Disclosed means the amount I want to reveal to others. The remainder is Hidden.
It's greyed out meaning I don't have access to it. Probably for institutional investors.

If you trade in US, you are allowed to use hidden orders if you want.
Note that display orders are given priority over hidden orders.

This post has been edited by Yggdrasil: Apr 9 2020, 05:27 PM

best price for buyer and seller is totally opposite. how to match?

Not exactly opposite. It matches the same way.
Price followed by Display>Hidden then Time.

That happens most of the time with Crypto coins. See the gap between their asking and bidding price.