As per the Exchange circular, the lot size of BANK NIFTY is being revised from 25 to 15 and here’s what you need to know.

Contracts after June 2023 monthly expiry will have revised market lot
The lot size of BANKNIFTY option contracts of and after July monthly expiry shall be revised from 25 to 15. Weekly contracts up to the weekly expiry of 20th July (6th, 13th and 20th July) will continue to use the old lot size of 25.

July future contract will use the new lot size of 15.

What does it means for you:
If you have an open position in BANKNIFTY with July 27th and beyond expiry date, you will have to do one of the following before 30th June 2023:

Convert the position into multiples of 15
Have position(s) in multiples of 15 - here your current 3 lots (25 x 3 = 75) will then become 5 lots (15 x 5 = 75)
Square off the existing position, if it is not in multiples of 15

If your remaining quantity is not in multiples of 15, you will not be able to square off your position and they will expire worthless.

Kindly plan your trades accordingly. You can also get more details by reading the circular here.

Looking for more information? Learn more about lot sizes and what they mean here.