An order book is a real-time list of all outstanding buy and sell orders for a security, organized by price level. It shows the bid (buy) side and ask (sell) side, revealing market depth—how many shares are available at each price. Traders use order books to gauge supply and demand before executing trades.
- Lists all pending buy and sell orders by price
- Shows market depth and liquidity at each level
- Helps identify support, resistance, and execution strategy
How Order Books Work
Order books organize supply and demand:
Order Book Example (HDFC Bank):
SELL SIDE (Asks):
Price | Quantity | Orders
₹1,605 | 2,500 | 8
₹1,604 | 4,200 | 12
₹1,603 | 6,800 | 15
₹1,602 | 3,500 | 10 ← Best Ask
BUY SIDE (Bids):
Price | Quantity | Orders
₹1,601 | 5,200 | 14 ← Best Bid
₹1,600 | 8,500 | 22
₹1,599 | 4,100 | 11
₹1,598 | 2,800 | 9
Spread: ₹1,602 - ₹1,601 = ₹1 (0.06%)
Quick Reference: Order Book Terms
| Term | Definition |
|---|---|
| Best Bid | Highest price buyers will pay |
| Best Ask | Lowest price sellers will accept |
| Spread | Difference between best bid and ask |
| Depth | Quantity available at each level |
| Market Depth | Total orders across all levels |
| Level 2 | Full order book (vs Level 1: best only) |
Example: Reading Market Depth
Scenario Analysis:
Order Book State:
Bids: 50,000 shares across ₹100-99
Asks: 10,000 shares across ₹101-102
Analysis:
- More buying interest than selling
- Strong support around ₹100
- Light resistance above ₹101
- Price likely to test upside
Action:
- If buying: May get filled near ₹101
- If selling: Good demand to absorb sells
An order book shows all pending buy and sell orders at each price level. It reveals market depth—how much volume exists to absorb trades. Large bid orders suggest support; large ask orders suggest resistance.
Order Book Analysis
Support and Resistance
Large bid orders create support—price bounces when hitting buy wall. Large ask orders create resistance—price struggles to break through sell wall.
Absorption
Watch if large orders get filled (absorbed) or if price bounces. Absorption of sell orders is bullish; absorption of buy orders is bearish.
Order Flow
Track how orders are added and cancelled. Increasing bids is bullish; increasing asks is bearish.
Imbalance
If bid volume far exceeds ask volume, buyers are more aggressive. Price tends to move toward the side with less volume.
Order Book Limitations
Hidden Orders
Iceberg orders show only a fraction. True depth may be hidden.
Spoofing
Fake orders placed and cancelled to manipulate perception. Illegal but happens.
Speed
Order book changes in milliseconds. What you see may be stale.
Not Predictive
Large orders don’t guarantee price direction. They can be pulled anytime.
Using Order Book for Trading
Execution Planning
See where liquidity exists. Place orders where depth supports good fills.
Stop Placement
Identify where large orders cluster—prices often bounce there.
Entry Timing
Wait for order book to support your direction before entering.
Size Decisions
If depth is thin, trade smaller to avoid moving price.
Common Mistakes
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Trusting the book blindly – Orders can be fake, hidden, or cancelled instantly.
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Front-running large orders – Sophisticated traders know and may pull orders.
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Ignoring time priority – Same price orders fill first-come-first-served.
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Over-analyzing – Order book is one input, not the only one.
How JournalPlus Supports Analysis
JournalPlus lets you note order book conditions when entering trades, helping you review whether your order book reads were accurate.
