Lot Size and Expiry Days in Index Options

Index Options have grown exponentially in popularity in India. With instruments like NIFTY, BANKNIFTY, and FINNIFTY, retail and institutional traders now have powerful tools to speculate, hedge, or diversify their exposure. This blog unpacks everything you need to know about Index Options, their lot sizes, and expiry schedules.

What Are Index Options?

An Index Option is a derivative contract that draws value from the underlying index like the NIFTY 50, BANK NIFTY, among others. They are European-style options, which means the exercise can only be done at expiry, and since they are cash-settled, there is no actual exercise of shares.

There are two types of index options:

• Call Options: The right to buy the index at a particular price. 
• Put Options: The right to sell the index at a particular price.

How Are Index Options Useful?

For example, if you expect the banking sector to outperform in the short term, trading BANKNIFTY options can offer leveraged exposure without needing to buy multiple banking stocks.

Current Index Options Lot Sizes (Jun–Aug 2025)

Lot size refers to the minimum number of units you need to trade in an options contract.

Note: Lot sizes can be revised quarterly by the NSE based on the price movement and liquidity of each index.

Expiry Schedule – Weekly & Monthly

Expiry refers to the date on which the option contract ceases to exist. Each index has weekly and monthly expiries, providing frequent opportunities to trade.

🛑 If the expiry day is a trading holiday, it will be preponed to the previous trading day.

Why Are Lot Sizes Important?

• Margin Requirements: Smaller lot sizes mean smaller margin requirements; basically, good for the retail trader.
• Scalability: Institutional traders can build large positions efficiently using multiple lots.
  
• Volatility Management: Changing lot sizes affects liquidity and volatility. E.g., a jump in MIDCPNIFTY lot size from 120 to 140 may affect spread and order book depth.

Key Features of Popular Index Options

NIFTY 50

• India’s benchmark index.
• Broad market exposure.
• Most liquid options contract.

BANKNIFTY

• Representing 12 major banking stocks.
• Higher volatility, so higher returns (and risks).
• Best intraday traders.

FINNIFTY

• Represents 20 financial services stocks.
• A sector-specific exposure.
• Good for weekly income generation strategies.

MIDCAPNIFTY

• Comprises 50 midcap stocks.
• Great for positional traders.
• Higher interest by options writers.

NIFTY NEXT 50

• Consists of stocks ranked 51–100 on NSE.
• Works as a feeder index for the NIFTY 50.
• Lower lot sizes mean retail interest.

BSE Derivatives: SENSEX & BANKEX

BSE offers derivative contracts on SENSEX and BANKEX, but trading volumes are comparatively lower than NSE. These instruments are generally used by arbitrageurs or long-term hedgers.

Risk Factors to Consider

• Time Decay (Theta): As the expiry date closes in, options lose their value.
• Volatility Risk: Whenever a sudden news arises in the market, an instant spike in implied volatility occurs.
• Liquidity Gaps: Some of the index options may not be very liquid. 
• Margin Requirements: Make sure that you are aware of the span + exposure margins before placing your trades.

Trading Tips

1. Use Weekly Options for short-term directional trades.
2. Monthly options suit swing and positional trades better.
3. Stick to liquid contracts (NIFTY, BANKNIFTY) for less slippage.
4. Be aware of the changes in lot size every quarter.

Final Thoughts

Index Options are powerful instruments in the hands of learned traders and investors. By understanding lot sizes, expiry days, and the characteristic features of each index, you will be in a position to frame a strategy that serves your financial goals.

Whether you are:

• Writing options for income, 
• Buying options for momentum plays, 
• or hedging long-term equity exposure… 

👉 Index options can bring flexibility and depth to your trading portfolio.