The Same Price Can Appear Multiple Times Over Time

Reading time: 3.5-4.5 min

In earlier lessons, the same price often appeared more than once within a single execution sequence.
That can create the false impression that a price is a persistent state rather than a sequence of discrete events.

Here, the same numeric price reappears later in the trade tape, separated by time and by changes in the book.

Each appearance is a separate execution event.

The reported price is $20 from the most recent trade at 9:19

No trade is occurring now.

Stage 1. The Book Changes Without Any Trade

Event: At 9:25 a seller submits an order to sell 4 apples at $22

No trade occurs because there is no bid at $20 $22 or any higher price.

The reported price remains $20

Event: At 9:26 a buyer submits an order to buy 5 apples at $16

No trade occurs because the highest bid is $16 and the lowest ask is $20

The reported price remains $20 even though no trade has occurred since 9:19

Stage 2. A New Bid Arrives at an Existing Price

Event: At 9:30 a buyer submits an order to buy 2 apples at $20

This new bid overlaps the existing asks at $20

Execution can proceed.

Stage 3. A New Trade Is Recorded at $20

Execution 1

1 apple is exchanged at $20 against the ask recorded at 9:10

A - the ask recorded at 9:10 is fully executed and removed.
B - the bid recorded at 9:30 is reduced from 2 apples to 1 apple.
C - a trade is recorded at 9:31 for 1 apple @ $20

The reported price is $20 again, now set by the new trade C at 9:31

Execution 2

1 apple is exchanged at $20 against the ask recorded at 9:11

D - the bid recorded at 9:30 is fully executed and removed.
E - the ask recorded at 9:11 is reduced from 6 to 5 apples.
F - a trade is recorded at 9:32 for 1 apple @ $20

The bid submitted at 9:30 has no remaining quantity.

Execution stops.

Summary — Repeated Prices Are Separate Events

The trade tape now contains multiple entries at $20

These entries are not one continuous “$20 level.”

They are separate records of separate executions, occurring at different times:

$20 was recorded at 9:19
$20 was recorded again at 9:31
$20 was recorded again at 9:32

Between 9:19 and 9:31 the book changed, but no trade occurred.

Past trades do not affect how future executions are matched, even if the price is the same. A previous trade at $20 does not influence whether or how a later trade at $20 occurs.

The price appears again only when new matching orders cause a new execution at that value.

Conclusion

A price is not a persistent market condition.

It is a value written to the trade tape when a trade occurs.

The same numeric price can reappear later, even after other orders were added and even when no trades occurred in between.

Each appearance is a distinct execution event, recorded separately.