JC Penny Co. had filed a prospectus for the sale of the entire stake of of one of its biggest investors, Bill Ackman.

The document contained the intended sale of approximately 39.1 million shares of common stock of the activist investor's company, Pershing Square Capital Management LP. This was according to a filing today with the US Securities and Exchange Commission. The stake was approximately 18% of the Texas-based retailer's total shares, shown through a data compiled by Bloomberg.

Earlier this month, Ackman had agreed with the retailer company on its planned stake sale last November. This was after Ackman's resignation from the board of directors at JC Penny. This was due to a dispute with his fellow directors.

JC Penny shares plunged by 1.1% to USD13.230 per share at 4:13pm in New York.

Billionaire and activist Bill Ackman previously acknowledged his mistakes of bets on retailers. He said that he had failed in three retailers including Target, Borders Group, which is now bankrupt and JC Penny Co.