What is Rights Agreement Aka "Poison Pill"?

An anti-takeover arrangement often established by a company in anticipation of a hostile takeover attempt. The company appoints a Rights Agent who will issue Rights Certificates to each shareholder at the time of the takeover attempt. The shareholder may then exercise these rights to receive additional shares of stock and/or debentures, making the target company more expensive to acquire as a result of the additional shares outstanding, or the additional debt.