Corporate actions including bonus, rights, mergers/demergers, dividends, splits, amalgamation, and consolidations will lead to adjustments in the futures and options contracts of the primary stock.
The basis for any adjustment for corporate actions shall be such that the value of the position of the market participants, on the cum and ex-dates for the corporate action, shall continue to remain the same as far as possible.
These adjustments will cause variations in base price, market lot, and option strike values based on the adjustment parameters. In several scenarios, adjustments could lead to change in the date of contract expiry, i.e., the contract might be closed before the expiry date and the adjusted contracts will be traded.
The adjustments will be carried out according to the type of corporate action involved. Also note, that adjustments for corporate actions would be applied on all the open positions.