Orders execution and priority

[Student]

Hi all,

Went searching on the ASX on the rules on how orders are executed and couldn't find anything, so does anyone know where this sort of information is available?

For example, say two people (A and B) have bids of A: 10000, B: 20000 shares at $1. "A" placed the order first, "B" placed the order second.

Someone places an order to sell 10000 at $1. How is the order split between A and B?

Does it matter if both orders were placed at or before pre-open?

 

[Trembling Hand]

Hi all,

Went searching on the ASX on the rules on how orders are executed and couldn't find anything, so does anyone know where this sort of information is available?

For example, say two people (A and B) have bids of A: 10000, B: 20000 shares at $1. "A" placed the order first, "B" placed the order second.

Someone places an order to sell 10000 at $1. How is the order split between A and B?

Does it matter if both orders were placed at or before pre-open?

A. gets all the order. It’s a simple first in first filled system. Think of it as a Line up for any product the ones that got in line first get served first. You just have to wait your turn or place an 'at market' order to get filled with what ever is available.
Have a look at a market detail screen if your broker supplies that. You can see all the orders in the book and where they are in the line. Here’s one for NAB

 

[Student]

Thanks for the reply. In that case I'd like to ask how something eventuated today:

Prior to open I saw a bid for 35k at 0.17, and no sellers at 0.17

I place an order to sell 35k at 0.17. Market depth shows my order at 0.17, the buyers at 0.17 and no other orders.

So I wait until open.

But somehow, my order only gets part-filled at 0.17, the rest went to someone else.

Could it be that someone slipped in a smaller limit order at 0.165 and swiped most of the order at 0.17 at open?

Any ideas on how can I best avoid this in the future?

 

[Trembling Hand]

Thanks for the reply. In that case I'd like to ask how something eventuated today:

Prior to open I saw a bid for 35k at 0.17, and no sellers at 0.17

I place an order to sell 35k at 0.17. Market depth shows my order at 0.17, the buyers at 0.17 and no other orders.

So I wait until open.

But somehow, my order only gets part-filled at 0.17, the rest went to someone else.

Could it be that someone slipped in a smaller limit order at 0.165 and swiped most of the order at 0.17 at open?

Any ideas on how can I best avoid this in the future?

Yep that’s what happened.

Playing the open can be very hard. If you put in an offer at .16 there is nothing to stop the guy with the .17 bid dropping it down to .16 seconds before the open and you get .16!!

 

[Happy]

There is another possibility, that cross trade - XT took place.

Broker who has matching party within house or another broker, only wait for price to reach certain level, they trade between themselves or in house and report to ASX.

Legitimate transaction, frowned upon by small traders but part of ASX system.