Icahn Builds Big Stake in J.C. Penney: Report

Carl Icahn has quietly amassed a significant stake in J.C. Penney, according to a report in The Wall Street Journal on Friday.

The report said the department store chain may be among the billionaire investor's top five holdings.

Neither Icahn nor J.C. Penney representatives were immediately available for comment.

It’s been a busy week for Icahn: On Thursday, the takeover king weighed in on Motorola's announcement that it might shed its wireless handset business -- which it pioneered before WWII. (Full Story: Motorola Shares Up as It Mulls Cell Phone Split-Off)

Icahn, listed as Motorola's No. 3 shareholder with a 3.3 percent stake as of Sept. 30, has urged the handset maker to break up to increase value for its investors.

"For many months I have been publicly advocating the separation of Mobile Devices from Motorola's other business and I am pleased to see that Motorola is finally exploring that proposal," Icahn said in a statement on Thursday.

But he said he remained determined to nominate some directors to Motorola's board at this year's annual meeting. "We believe Motorola is finally moving in the right direction but certainly still has a long way to go," Icahn added.

Last year, Icahn failed in his bid to win a seat on Motorola's board after a brutal proxy battle.