Term · Liquidity & Trading
Order-book depth
In briefOrder-book depth describes how many buy and sell orders sit across several price levels and how much volume can move before the price shifts noticeably. For small caps it shows the real executability, whereas a stock may look liquid on the surface.
Definition
The quantity of buy and sell orders across several price levels in the order book. Depth shows how much volume can be absorbed before the price moves noticeably.
How it is calculated
Formula. Not a balance-sheet formula; analysed via cumulative volume on the bid/ask side up to defined price distances.
Why it matters for small caps
In the small-cap segment stocks can appear liquid on the surface, although only a few shares sit at the best price; order-book depth shows the real executability.
Common misreadings
- It is confused with trading volume; volume is historical, order-book depth is the current market microstructure.
In the process
Frequently asked
What is order-book depth?
It indicates how much supply and demand are distributed across various price levels in the order book. Great depth means that high volumes can be traded without a strong price move.
How do you assess order-book depth?
You look at the cumulative volume on the buy and sell sides up to certain price distances. This shows how resilient the price is to larger orders.
Why must you not confuse depth and trading volume?
Volume is a historical figure, order-book depth shows the current market microstructure. A stock can be hard to trade despite volume when the book is thin.
Related terms
Sources
Primary
EUR-Lex – MiFID II, Richtlinie 2014/65/EU
https://eur-lex.europa.eu/eli/dir/2014/65/oj
https://eur-lex.europa.eu/eli/dir/2014/65/oj
Methodology
Education only, not investment advice. Ranges and thresholds are didactic orientation values, not an official standard.