Question about BID vs ASK at the start of Day Trade

Question

So I have been monitoring this IPO recently.
Day trade starts and we are allowed to post bid and asks for 30 minutes before the market officially opens.
I see asks for around 40 for 4500 shares. Lowest ask before market open.
Then I see a bid for 60 for 2000 shares. Highest bid before market open.
Sample Table below:
Bid-------------------------------------Ask
60$ for 2000 shares---------------------40$ for 4500 shares
59$ for 1000 shares---------------------55$ for 1000 shares
58$ for 1500 shares---------------------54$ for 1000 shares
For example the list above is the latest as the market opens.
Will the 40$ for 4500 shares fill in the 60$, 59$ and 58$ bids? Will it be calculated as
60 x 2000 = 120000
59 x 1000 = 59000
58 x 1500 = 87000
120000 + 59000 + 87000 = 266000$
OR......
40 x 4500 = 180000$ ?
Sorry for not so good english.

base64 · Answer

In most exchanges, there is only single opening price during opening auction. The single price should maximize the volume transacted / minimize the imbalance of market orders.
In your case, any single price at or between $40 and $60 can equally maximize the volume of 4500 shares.
How the single price can then be determined is depedent on the exchange.
Take NYSE as an example:

Determining Core Open Auction Price
If there are multiple prices at which the Total Imbalance can equally
execute, the Indicative Match Price will be based on the price closest
to the Auction Reference Price, including equal to the Auction
Reference Price itself when that is one of the prices available.
https://www.nyse.com/markets/nyse-arca/trading-info#core

The definition of Auction Reference Price is:

Rule 7.35C. Exchange-Facilitated Auctions
“Auction Reference Price” means: IPO or Direct Listing Auction:
A price determined under Rule 1.1(s)(1)(F)
https://nyseguide.srorules.com/rules/document?searchId=360953749&treeNodeId=csh-da-filter!WKUS-TAL-DOCS-PHC-%7B4A07B716-0F73-46CC-BAC2-43EB20902159%7D--WKUS_TAL_19401%23teid-44

Which refers to:

Rule 1.1. Definitions
For a security that is a new listing and does not have any
consolidated last-sale eligible trades on its first trading day, the
Official Closing Price will be based on a derived last sale associated
with the price of such security before it begins trading on the
Exchange.
https://nyseguide.srorules.com/rules/document?searchId=360953953&treeNodeId=csh-da-filter!WKUS-TAL-DOCS-PHC-%7B4A07B716-0F73-46CC-BAC2-43EB20902159%7D--WKUS_TAL_19401%23teid-2

Which is likely whichever price is closer to the IPO Offering Price.

Question about BID vs ASK at the start of Day Trade

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