Savient Pharmaceuticals Inc. adopted a stockholder rights plan with a 15% trigger to protect stockholder value amid an ongoing fight with debtholder Tang Capital Partners. A rights plan, also known as a poison pill, often is used to thwart potential hostile takeover offers by giving other shareholders the right to buy more shares at a discount if one shareholder buys a certain percentage of the company’s stock. If approved by holders next year, the plan will expire in 2015. Savient said its poison pill is designed to reduce the likelihood any person or group would gain control of the company by open marker accumulation or other coercive takeover tactics without paying a control premium for all shares. More specifically, the company pointed to recent efforts by certain convertible noteholders that are adverse to the best interests of the company.