Activist hedge fund manager William Ackman, who has been known for big bets on retailers and real estate, on Friday said his fund has taken a 16.5 percent stake in retailer JC Penney.

Unveiling one of his biggest investments in months, Ackman’s New York-based firm Pershing Square Capital Management said it now owns roughly 39 million shares of common stock in the Plano, Texas-based retailer.

The firm also entered into over-the-counter derivatives contracts know as total return swaps which are linked to the performance of an additional 602,600 common shares.

Pershing Square invests roughly $7 billion and ranks as one of the industry’s biggest and most prominent activist fund firms. Only last year, Ackman lost a bitter proxy fight with retailer Target, which had been his biggest single investment ever.

Pershing Square expects to speak with management, the board and other stockholders” about JC Penney’s business , assets, and financial conditions, it said in a regulatory filing.

JC Penney shares climbed 3.38 percent to $32.79 in early trading in New York, having surged 16 percent since the beginning of October.

JC Penney could not immediately be reached for comment.