To avoid being the target of a hostile takeover by a larger firm, a corporate board might adopt a defensive strategy called a shareholder rights plan. Such plans allow existing shareholders the right to purchase additional shares at a discount, effectively diluting the ownership interest of any new, hostile party. Most plans are triggered whenever one individual or entity obtains a certain percentage of total ownership, leading to the nickname "poison pill."
An example of a poison pill defense occurred in 2012, when Netflix announced a shareholder rights plan had been adopted by its board just days after investor Carl C. Icahn acquired a 10% stake. The new plan stipulated that with any new acquisition of 10% or more, any Netflix merger or Netflix sales or transfers of more than 50% of assets, existing shareholders can purchase two shares for the price of one.