Imagine stock for some company XYZ opened at $100 and then traded each hour 1000 shares with increase of $1 each hour: 1000 shares sold at 10am for $100/share, then 1000 shares sold at 11am for $101/share and so on. All daily transactions are:
1000 @ $100 (10:00am) 1000 @ $101 (11:00am) 1000 @ $102 (12:00pm) 1000 @ $103 ( 1:00pm) 1000 @ $104 ( 2:00pm) 1000 @ $105 ( 3:00pm) 1000 @ $106 ( 4:00pm)
It's obvious how that would look on hourly chart: constant volume and price steadily increases each hour. Also, assume that when there were no trades bid-ask spread was always +/- 1$, that is at 1:30pm bid/ask was 1000 shares on each side with $102 bid and $104 ask. Volume for the day is 7000 shares with $100 open, $106 close and average price for the day is $103. That's what happened on public exchange. Assume that the same XYZ stock was traded once at a dark pool in a single transaction of 100K shares at exactly 1:30pm at $100/share.
is it even possible that in dark pool a transaction would be executed at lower price than current bid/ask on public exchanges? Eg. if somebody placed 100K shares for sale at $100/share at 1:30pm would that be matched by current bid of $102 on public exchange, or the buy/sell books aren't connected in any way and dark pools may trade at price unrelated to current public price?
are dark pool trades related to L3 hidden orders or it's totally different unrelated thing?
all traders watching XYZ would see 1000 shares traded each hour and the price traded. What will they see on the tape at 1:30pm when 100K block gets executed at a dark pool at $100/share? Will everybody see price move down by $2 on huge volume or nobody will see anything until end of day? That is, will this trade be visible to all, will the price be visible, will the time of execution be visible and if it will be visible, when will it be?