Bill Ackman, the largest JCPenney investor, with about 18 percent, can start selling his stock in November, according to a filing yesterday.

The accord was part of Ackman’s departure from the board after a battle over the direction of the company, including how quickly to replace interim chief Mike Ullman.

JCPenney shares fell 3.1 percent, to $13.40, at the close in New York yesterday.