A number of Icahn-controlled companies said in a statement and a securities filing that they had acquired the 19.8 million shares "in the belief that the common shares of Lions Gate were undervalued" and that they may buy more shares.

The Icahn affiliates said they had discussions with Lions Gate Chief Executive Jon Feltheimer and Vice Chairman Michael Burns and may seek to add nominees to the company's board by removing directors or expanding the size of the board.

Icahn could try to take those actions at the company's next annual meeting, the statement said.

The shares of the studio behind the "Saw" franchise leaped 9 percent to $5.69 in after-hours trading following the news, against a regular close of $5.22.

Caris & Co analyst David Miller said investors agreed with Icahn that, "the stock is trading well below the sum of its parts."

Icahn tried unsuccessfully this year to buy $325 million worth of convertible notes issued by the studio in the hope of converting them to equity to raise his stake to 29 percent.

He had few takers for his discounted offer, which expired on May 1.

Lions Gate warned in March that a change in control of the company could cause a debt default and accelerated payment obligations on its credit facility.

Icahn has aggressively boosted his stake in the Santa Monica, California-based studio since last October, when he owned a 3.7 percent stake, securities filings show.

Icahn has criticized Lions Gate for overspending on overhead and for its $255 million purchase of the TV Guide cable channel, and has warned he may wage a proxy battle to rein it in. Lions Gate subsequently sold a 49 percent stake in the channel for about $123 million last month.

The company's largest investor, Mark Rachesky, whose MHR Fund Management LLC controls a 19.99 percent stake, has said it is "principally supportive" of Lions Gate's management and publicly stated strategies.

MHR has said it had talks with Lions Gate about nominating a candidate -- possibly Rachesky -- to the company's board.

This month, Lions Gate reported a fiscal fourth-quarter net loss of 25 cents per share, compared with a profit of 22 cents per share a year earlier, on a 10 percent decline in revenue.