What is Ask Price and Bid Price in the Stock Market?

Highlights

• Understand how bid and ask prices form the foundation of stock trading on NSE and BSE.
• Learn how bid-ask spreads directly impact your transaction costs beyond brokerage fees.
• Discover SEBI’s tick size regulations that govern minimum price movements in Indian markets.
• Compare liquidity differences between large-cap and small-cap stocks through spread analysis.

Introduction

Every time you buy or sell a stock, you’re stepping into a fast-paced negotiation between two invisible forces – the bidder who wants it cheaper and the seller who wants it higher. That tiny gap between them? It’s not random. It’s the bid-ask spread, and it quietly decides how much you really pay (or earn) every time you trade.

Understanding Bid and Ask Price

The bid price represents the highest price a buyer is willing to pay for a security at a given moment in the market. It’s essentially what buyers are offering right now.

The ask price (also called offer price) is the lowest price a seller is willing to accept for a security at any given moment in the trading system. This is the minimum sellers will take.

In NSE’s trading system, if a stock shows a bid at ₹1,450.00 and an ask at ₹1,452.50, buyers are offering ₹1,450, whilst sellers want a minimum of ₹ 1,452.50. No trade happens until someone bridges this gap – either a buyer pays the ask, or a seller accepts the bid.

What is Bid-Ask Spread?

The bid-ask spread represents the difference between the ask price (the lowest price a seller is willing to accept) and the bid price (the highest price a buyer is willing to pay) for a security.

It is calculated using the formula:

Bid-Ask Spread = Ask Price − Bid Price

For example, if the bid price of a stock is ₹1,450 and the ask price is ₹1,452.50, the spread would be:

₹1,452.50 − ₹1,450 = ₹2.50

On a ₹1,450 stock, this spread represents roughly 0.17% of the trade value, which can be considered an implicit transaction cost before brokerage, taxes, or other trading fees.

This spread exists because buyers and sellers have different price expectations, and it often narrows in highly liquid stocks while widening in less frequently traded securities.

Correct Tick Size Structure (NSE – 2025 Revision)

Tick size refers to the minimum price movement allowed for a security on the exchange. According to the latest NSE circular, effective April 2025, tick sizes are determined based on the price of the security. For example, securities priced below ₹250 have a tick size of ₹0.01, while higher-priced securities have progressively larger tick sizes.

This framework helps maintain efficient price discovery and orderly market movements, particularly for high-value stocks where larger tick sizes can improve trading efficiency.

How Bid-Ask Spread Affects Your Trading Costs

For a retail investor placing a market order, buying 100 shares at the ask price of ₹1,452.50 and selling at the bid price of ₹1,450 (without any price movement), the spread cost alone is ₹250, excluding brokerage and taxes.

Here’s the calculation:

Buy: 100 shares × ₹1,452.50 = ₹1,45,250
Sell: 100 shares × ₹1,450 = ₹1,45,000

Immediate loss due to spread: ₹250

This cost arises because market orders execute instantly at the best available prices (ask for buying, bid for selling).

In contrast, with limit orders, you can control your execution price and potentially avoid paying the full spread – though execution is not guaranteed.

High-liquidity stocks like Reliance Industries or TCS typically show spreads of ₹0.05–₹0.50 (0.001–0.01%), while low-liquidity small-cap stocks may show spreads of 1–3% due to fewer buyers and sellers. This liquidity difference significantly impacts your actual returns.

Factors That Influence Bid-Ask Spread

Trading volume also plays an important role in bid-ask spreads. Highly liquid stocks with large trading volumes typically have tighter spreads, making it easier for investors to buy or sell without significantly affecting the price.

In contrast, stocks with lower trading volumes often experience wider spreads, reflecting lower liquidity and higher transaction costs. Academic research consistently shows an inverse relationship between trading volume and bid-ask spreads, meaning spreads tend to narrow as market activity increases.

Market volatility causes spreads to widen. During high volatility periods, market corrections, and earnings announcements, bid-ask spreads can widen 2-5 times normal levels as market makers increase spreads to manage risk.

Time of day matters too. Spreads tend to widen during market open and close due to order imbalances, narrowing during mid-day trading when liquidity peaks. Understanding these patterns helps you time trades for better execution.

Key Takeaway for Investors

Efficient price discovery through tight bid-ask spreads indicates market health. SEBI monitors these spreads through market maker obligations and surveillance systems to protect retail investors. Whilst you cannot eliminate spread costs, choosing liquid stocks and avoiding volatile periods helps minimise this hidden expense.

Focus on high-volume stocks for day trading and accept wider spreads for long-term small-cap investments where holding period matters more than entry precision.

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