If a company makes a bid for LSG for $5.00, LSG would automatically double its outstanding shares and offer present shareholders to double their position at half the price. If shareholder X has 100,000 shares he/she could buy another 100,000 shares for $2.50. The purpose is to deter week takeover bids. as for an expiry date, I don't think LSG has one. For HOC to go over 19.9% ownership, the poison pill would come in effect and is why they want it removed so the deal can be done.