JCPenney yesterday said it had adopted a one-year stockholder rights plan to protect itself against any future coercive takeover efforts.

The department-store chain, which is struggling to reverse a massive sales slide, said the “poison pill” plan was not in response to any particular takeover attempt. The provisions would block any single investor from owning more than 10 percent of the retailer’s shares.

The move comes after a public feud earlier this month between Penney’s board and largest shareholder, William Ackman. The owner of nearly 18 percent of the company from shares he bought in 2010, Ackman has since resigned from the board. This week he said he might sell his stock.