apparently you will need to refer to Listing Rule 6.23.3 which...

apparently you will need to refer to Listing Rule 6.23.3 which states "A change [to an option] which has the effect of reducing the exercise price, increasing the period of exercise or increasing the number of securities received on exercise cannot be made."


http://www.asx.com.au/ListingRules/chapters/Chapter06.pdf



however, rule 6.23.4 suggests that a vote by the ordinary shareholders can change the expiry date. thus, a vote by ordinary shareholders is the only way within ASX rules to do so.

more as i find out more in a day or 2.