EXR Trading 2021, page-989

Simply put the money flows from the highest level to the lowest level until they reach 'evens'. Once they reach evens that becomes the price of the opening or closing auction.

Using the example of above the 19.5c buy order soaked up the 16.5c sell order, with the remained of his 7,050 volume then being filled in the 17.5c sell orders.

The next order for 19c - because it's above the 17.5c still on offer then fills itself with the 17.5c shares being offered.

Likewise the buy orders at 18c fill up at 17.5c.

The total volume of the 19, 18.5 and 18c orders was 182,895 - then we get to the 17.5c buy orders. Because there is a surplus volume of 17.5c buy orders they match with the remaining 17.5c sell orders and that becomes the price o the opening auction.

The advantage of putting your buy order above the indicative price is it means it will get filled first at the auction price. For example, if you really wanted to buy EXR this morning you could have put in a bid for $1 dollar per share, but that would have been filled at 17.5c. It just puts you to the top of the queue.

Likewise, if you wanted to sell - like the fellow at 16.5c, all he is doing id quaranteeing his sale will go through first, but still at the auction price, which today was actually 18c.

Clear as mud?