Question about order within market depth

[cc77]

Had a strange trade executed today during the close. I won't mention the stock but here is the scenario with very similar numbers

Stock XYZ opens at 5.50 and I place a sell limit order of 2000 @ 5.55 (not to expire today). I see the market depth increased to ~7000 @ 5.55 after my order.

Stock fluctuates between 5.30 - 5.50 all day up until 4pm but closes 5.55 right after the auction. Later, checked my account and found out I was only partially filled? That's fine but the strange bit was that the volume during the close was 90000?!?

Why was I only partially filled?!? Correct me if I'm wrong but I thought it was first in dressed best OR maybe I've completely misunderstood this game and whoever has the largest pending trade (price * shares) in the queue gets first dibs?

 

[skyQuake]

Had a strange trade executed today during the close. I won't mention the stock but here is the scenario with very similar numbers

Stock XYZ opens at 5.50 and I place a sell limit order of 2000 @ 5.55 (not to expire today). I see the market depth increased to ~7000 @ 5.55 after my order.

Stock fluctuates between 5.30 - 5.50 all day up until 4pm but closes 5.55 right after the auction. Later, checked my account and found out I was only partially filled? That's fine but the strange bit was that the volume during the close was 90000?!?

Why was I only partially filled?!? Correct me if I'm wrong but I thought it was first in dressed best OR maybe I've completely misunderstood this game and whoever has the largest pending trade (price * shares) in the queue gets first dibs?

People frontrun you in that close.

ASX is Price then Time priority.
You had Time priority, other orders at 5.55 will go behind u.

If someone puts in an ask at 5.50, they will have price priority and get in ahead of you.

So in the match their order got filled in front of you

 

[nioka]

Apart from those that get in ahead of you at the closing auction there are xtrades made when a broker matches a sell and a buy within the brokerage. I was beaten at the open with an arder for CER which I thought had been filled but found out that the orders filled were cross trades and that made me "cross" trader with my order unfilled. Later in the day my order was filled with a cross trade also.