Bonuses, rights, extra-ordinary dividends, mergers/demergers, amalgamations, splits, and consolidations all cause changes in the futures and options contracts of the underlying stock undertaking the corporate action.

The foundation for any adjustment for corporate actions shall be such that, as far as practicable, the value of market participants' positions on the cum and ex-dates for the corporate action remains unchanged.
Depending on the adjustment factor, changes to the base price, option strike prices, and market lot will occur. In many circumstances, contract adjustments will result in a change in the contract's expiry date, i.e. the contract will be forced closed before the expiry date and the updated contracts will trade instead.

Depending on the nature of the corporate action, the adjustments could be made to any or all of the above. All open jobs would be subject to the adjustments for corporate actions.