Generally, a poison pill issues rights to all existing shareholders, with the exception of the hostile suitor, to acquire stock of the target (or of the aggressor upon a subsequent merger) at prices significantly below market. These rights are triggered by certain specified events, such as the announcement of a cash tender offer or the acquisition by an outsider of a specified percentage of the target's shares. Thus, a poison pill is effective because it dilutes the economic interest of the hostile suitor in the target, making the transaction both economically unattractive and impractical if pursued on a hostile basis.