What happen to Nifty December 2015 Contracts?? An important information...

What happen to Nifty December 2015 Contracts ( Call n Put ) after changing lot size to 75, currently Lot size is 50 ?

So if you are holding 50 Nifty Dec CE/PE or any multiple of 50 (current lot size of Nifty for long dated options is 50 and not 25 like everyone thinks) after the end of this expiry on 24th Sept, the new lotsize of Dec will be 75. What this means now is that you will not be able to exit the 50 Nifty CE/PE that you hold after this thursday. 

So for example

1. If you hold 50 Nifty Dec calls after this expiry. You will not be able to convert this into a multiple of 75, and hence u will not be able to sell and will be forced to hold the position till Dec expiry. 

2. If you hold 100 Nifty Dec calls (2 lots) after this expiry, you will be able to sell only 1 lot of 75, and u will be forced to hold the remaining 25 till Dec expiry. 

So, if you want to continue to hold this position into next month, ensure that you are holding an option position which is a multiple of 75 (new lot size). So if you have 50 Nifty, buy another 100 to make it 150 (multiple of 75). Or just square off all positions and take a fresh position after the Sep expiry. 

Remember that you have to get this done before the end of September expiry on Thu, 24th Sep 2015.