Family Dollar Stores, Inc.(NYSE:FDO) shares were higher over 15% in recent trade after adopting a so-called poison pill – a shareholder rights plan that protects the company from being taken over or controlled by one group or person without paying a premium to other shareholders. 

FDO is trading in the upper half of the 52-week range between $55.64 and $75.29. 

The plan, which was adopted after activist investor Carl Icahn said he has a 9.4% stake in the company, has a 10% ownership threshold but may be amended, Family Dollar said in a statement. 

“The plan applies equally to all current and future stockholders and is not designed to prevent an offer to acquire the company, but rather to allow the Board adequate time to consider any and all alternatives,” the company said. 

Under the plan, for each share owned, Family Dollar will issue a unit consisting of one-thousandth of a share of Series A Junior Participating Preferred Stock at a Purchase Price of $300.00 per unit , subject to adjustment.