The value of the futures contracts on Nifty may not be less than Rs. 2 lakhs at the time of introduction. The permitted lot size for futures contracts & options contracts shall be the same for a given underlying or such lot size as may be stipulated by the Exchange from time to time.
Check this link:- http://www.nseindia.com/products/content/derivatives/equities/cnx_nifty.htm
Gud one Linekar!. I can’t really comment on Index derivatives. I am presuming the lot size for Equity derivatives is decided on the following points-
Market Cap of the company in the exchange.
Degree of participation of the company’s shares in the exchange.
Whether the share is constituent of an Index or not.
As Praveen has rightly put, the guideline that NSE follows is to keep the value of the contract above Rs 2lks at the time of introduction, this is again a regulatory requirement from SEBI. As and when the value of stock goes up quite a bit above Rs 2lks, the contract size is reduced to bring it back to around Rs 2lks. For example Nifty futures when first introduced was a lot size of 100, but when Nifty went to 5000+ this lot size was reduced to 50.