AhoyI'm not sure there is a 'legal' requirement. Companies...

Ahoy

I'm not sure there is a 'legal' requirement. Companies develop a coy specific "Corporate Governance" policy which would contain such matters as blackout periods. However if they are buying/selling and are privy to market sensitive info they could be pinged for insider trading.

http://www.companydirectors.com.au/Media/Media+Releases/2009/Director+trading+recommendations+present+some+concerns.htm

and see ASX Listing Rules 3.19A

http://www.asx.com.au/ListingRules/chapters/Chapter03.pdf

I think.