Market Records
Before any offers to sell or buy apples are recorded, the records that define the market are established.
There are three separate ledgers each with a distinct role:
- Asks ledger
- Records all offers to sell apples that have not been filled or removed.
- Bids ledger
- Records all offers to buy apples that have not been filled or removed.
- Trade tape
- Records every completed exchange.
Taken together, these three ledgers are referred to as
the book
The trade tape records executed trades separately.
Taken together, these ledgers constitute the market records
If something is not written in the market records, it does not exist for the market.
In this tutorial, the price visible to the outside world is derived from the most recent trade recorded on the trade tape.
If no trade has occurred yet, no price is reported.
At the start, the market records are empty.
- No apples are offered for trade.
- No exchanges have occurred.
- No prices exist yet.
The market exists only as empty records, ready to record orders and trades.