Slowly at first. BANKNIFTY has no weekly options. Its options expire once a month, on the last Tuesday. Early in the month about 4 weeks are left. Take an at-the-money call, whose strike is closest to the index. If nothing moves, it loses about 15% of its price in the first week. The last week takes about 46%.
- Index
- BANKNIFTY
- Cycle
- BANKNIFTY monthly
- Starts
- 09:15 IST
- Runs for
- 23 trading days · About 7 hr 23 min at Normal speed
- Difficulty
- Advanced
- Date
- 27 May 2026
- Expiry
- BANKNIFTY 30 Jun 2026
- IV
- 13.88%
What is this market shaped like?
A BANKNIFTY month runs from the day after a monthly expiry to the next. This market starts near the beginning, with about 4 weeks left. For BANKNIFTY, a night counts as about 0.4 of a trading day. A weekend counts as about 0.8 of a trading day. BANKNIFTY's option prices usually expect a slightly bigger move than NIFTY's.
What is left of an at-the-money call's price, if nothing moves
| Where in the month | Calendar days left | Left of the starting price |
|---|---|---|
| Start | 27 | 100% |
| After the first week | 21 | 85% |
| Mid-month | 14 | 72% |
| Start of expiry week | 6 | 46% |
| Monday before expiry | 1 | 26% |
| Expiry day open | today | 17% |
| Expiry day 13:30 | today | 10% |
Nothing moves means the index stays still and IV stays the same. IV (implied volatility) is the size of move option prices expect.
The first week takes about 15%. The last week takes about 46%. So a monthly option feels slow early and fast at the end.
What will you see?
- Theta, the value lost to time, is small this early. 1 quiet day takes about 1.6% of an at-the-money call.
- So the index move matters more than time. In the 1-day version, BANKNIFTY needs to rise only about 22 points to pay for the day.
- Vega is how much an option's price changes when IV moves by 1 point, for example from 14% to 15%. A monthly option has more vega than a weekly one. So a change in IV matters more here.
Which version do you want?
Each version is the same kind of market with 1 thing changed. Choose one to start it.
- 1 day · Calm
- First week · Normal
- Whole month
The Whole month version runs 23 trading days, to the expiry close.
What should you try?
The exercise below covers day 1 only. This selected version runs longer.
Try this with 1 lot of 1 call. A lot is the smallest size you can trade.
- Buy 1 lot of the at-the-money call at the open.
- Hold it all day and note its price at the close.
- Compare the call's close price with its open price and BANKNIFTY's move.
What should you check afterwards?
- How much did the call's price change while you held it?
- How does a day here compare with a Thursday for a NIFTY weekly?
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