Stock Market · Options Theory

Weekly vs monthly expiries

India's option market offers both weekly and monthly expiries for major index products. Each has distinct characteristics that attract different types of traders and strategies.

Weekly expiries

Nifty: expires every Tuesday (weekly). NSE moved from Thursday in Sep 2025

Sensex: expires every Thursday (weekly), BSE

Characteristics:

• Premium is low (little time value, only days remaining)
• Gamma is very high. Small moves cause large percentage premium changes
• Theta decay is rapid. Premium erodes fast, daily
• Used by: intraday and swing traders, directional plays on events, short-term premium sellers

₹10–50Typical ATM weekly premium 3 days from expiry

High gammaa 0.5% Nifty move can double an ATM weekly option

Monthly expiries

Last Tuesday of each month for NSE (last Thursday for BSE Sensex). More liquidity, higher OI, larger premiums.

Characteristics:

• Higher absolute premium (more time value)
• Lower gamma, more gradual price changes
• Better for positional traders and structured strategies (spreads, condors)
• Where institutional hedging concentrates

₹200–500+Typical ATM monthly premium 3 weeks from expiry

Which is better?

> For option buyers: weekly offers high gamma leverage but extreme theta pressure. Monthly gives more time for the trade to work.

> For option sellers: weekly provides fast premium collection with frequent opportunities. Monthly offers larger absolute premium but exposure lasts longer.

The weekly options trap for beginners

The low absolute premium (₹20 option) makes weekly options seem like cheap lottery tickets. But the OI is lower outside Nifty, spreads are wider, and theta decay is brutal. Most beginners who exclusively trade weekly options lose consistently.

Takeaway. Weekly options have low premium, high gamma, rapid decay, suited for short-term directional trades. Monthly options have more time value, lower gamma, better for structured strategies and positional plays.