Liquidity is the ability to transact without large price impact
A liquid market lets you buy or sell meaningful size with relatively small execution cost. Liquidity has several dimensions: trading activity, bid-ask spread, available depth, resilience after trades and the ability to transact during stressed conditions.
Volume is not the same as liquidity
A stock can have high daily volume but still have a wide spread or shallow depth at the exact moment you need to trade. Conversely, a security can have modest volume but good execution for a small order.
Spread, depth and market impact
Spread is the gap between quoted bid and ask. Depth describes how much quantity is available around quoted prices. Market impact is the price movement caused by your own order. These interact: a large order can consume several price levels.
Worked example
If the best offer is ₹100.10 for 500 shares but you need 10,000 shares, the displayed ₹100.10 is not necessarily your execution price. Your order may consume higher offers. The relevant cost is the full execution path, not just the first quote.
Why liquidity matters more in stress
Normal-day liquidity can disappear when markets gap, news arrives or many participants attempt to exit simultaneously. This is why position size should consider exit liquidity, not only entry convenience.
Investor and trader checklist
- Average turnover
- Typical bid-ask spread
- Depth at relevant price levels
- Free float and concentration
- Historical behaviour during stress
- Your own order size as a percentage of normal activity