CKE Restaurants Inc. said Monday its board approved a one-year poison pill a stockholder rights plan it claimed would protect current stockholder interests in any unsolicited acquisition attempt.

CKE, whose share price has declined 31 percent over the past year, said the Carpinteria-based operator of Carl’s Jr. and Hardee’s restaurants currently was not facing such an effort.

“Our board of directors has deliberated about whether to adopt a plan for several months, in light of the recent market volatility affecting the share prices of many companies, including CKE,” said Chairman Byron Allumbaug in a statement. The board’s decision is “a means to guard against abusive takeover tactics generally.”

Under the plan, shareholders will receive a distribution of rights to purchase shares of a newly authorized series of preferred stock in the event of a tender offer for at least 15 percent of CKE’s common stock. The plan applies to shareholders of record as of Wednesday and will be in force until Dec. 31.

CKE shares were up 2 cents, or less than 1 percent, to $8.86 in morning trading on the New York Stock Exchange.