Why 5-Level Order Book Helped a 10,000 KRW Midcap?

One condition only!!!

The optimal order book setting varies by situation.

You must understand tick size first to use this in practice.

Retail trader: "How many levels are just right on the order book?"

The correct answer is 'it depends on the situation', and the calculation follows below.

What is order book setup?

Order book setup means how many bid and ask levels to display and the price unit shown.

Tick size refers to the order price interval, the exchange-defined minimum price unit.

Why does this matter?

It determines execution speed and execution probability.

A narrow view shows more immediate levels but makes you miss sudden moves.

A wide view shows broader depth but loses in speed and agility.

Practical example, hypothetical numbers

Situation: midcap by market cap, current price 10,000 KRW, tick size 10 KRW.

Setting A: 5 levels (5 each side), easy to spot order gaps, fast execution.

Setting B: 20 levels, shows depth, better for large orders but slower to react.

Assumption: 5,000 shares traded per minute, average execution price swing 30 KRW.

A expected execution probability = 0.8 (advantage from fast reaction).

B expected execution probability = 0.6 (slower due to depth checking).

In low spread, high volume windows, reduce visible levels to prioritize reaction speed.

Execution probability means the chance your submitted order actually fills.

How to factor tick size?

Wide ticks create larger price steps, so each step is meaningful.

Narrow ticks increase micro price competition and psychological stress.

Practical tip: when volatility rises, lower the number of visible levels to favor speed over tick detail.

A common misconception: more levels equals safer?

That is only partially true.

Deeper view reveals large liquidity but increases the risk of missing fleeting trades.

Decide whether your priority is execution speed or informational depth first.

So what to remember

→ 1. High liquidity stocks: reduce visible levels to prioritize reaction speed.

→ 2. Preparing for large trades: increase visible levels to inspect depth.

→ 3. With wide ticks, a one-tick difference matters, so use price-splitting strategies.

This is for reference only.

PickStock 💡

※ This article is for informational purposes and is not investment advice.
※ Investment decisions and responsibility belong to the investor.
※ Figures reflect the time of writing and may change.