Aug. 14 (Bloomberg) -- Billionaire investor Carl Icahn, known for pushing company executives to make changes to improve their stock prices, bought stakes in Take-Two Interactive Software Inc. and Symantec Corp. in the second quarter.

Shares of Take-Two, publisher of the ``Grand Theft Auto'' video games, and Symantec, the No. 1 anti-virus software maker, jumped after Icahn disclosed the holdings today in a regulatory filing. Both stocks have trailed the market this year.

Icahn also acquired a stake in health insurer Cigna Corp. and added to his holdings in media giant Time Warner and biotechnology company ImClone Systems Inc. Susan Gordon, his assistant in New York, said he wasn't available for comment.

The 70-year-old investor built a fortune estimated at $8.5 billion by Forbes magazine, in part by buying into companies he deemed undervalued and pressing for changes such as asset sales and stock buybacks. A veteran corporate raider turned self- described shareholder activist, his most recent victory was at KT&G Corp., South Korea's biggest tobacco maker, which earlier this month agreed to return $2.9 billion to investors.

Take-Two's stock price rose 68 cents, or 6.4 percent, to $11.30 at 4 p.m. in Nasdaq Stock Market composite trading. Icahn owns 800,000 shares, or 1.1 percent, of the New York-based video- game maker, according to the filing. Before today, the shares had plunged 40 percent since the start of the year.

The company has been hurt by revelations that sexually explicit scenes were hidden in its ``Grant Theft Auto: San Andreas'' game. In June, the company said it received subpoenas from the Manhattan District Attorney's office for documents related to earnings disclosures and the hidden scenes.

Time Warner

Icahn bought 6 million shares, or 0.6 percent, of Symantec, according to the U.S. Securities and Exchange Commission filing. The shares rose to 16 cents to $17.74 in Nasdaq trading.

Last month Symantec reported a gain in consumer sales and forecast higher than estimated revenue in the current quarter. Shares of the Cupertino, California-based company have gained 1.4 percent this year, compared with the 1.6 percent increase by the Standard & Poor's 500 Index.

``We've received no indication that he has any intention other than being a passive holder,'' Symantec spokeswoman Yunsun Wee said in an interview. ``We've told his representative that we welcome him as an investor and agreed with his view that Symantec is undervalued.''

In the second quarter, Icahn added 4.8 million shares to his position in Time Warner. He now holds about 1.6 percent of the company. In February, Icahn abandoned a bid for control of the board of the world's largest media company.

Buying More

Other new purchases included 1.1 million shares of Cigna, or about 1 percent of the fourth-largest U.S. health insurance company. Philadelphia-based Cigna shares fell 94 cents to $105 in New York Stock Exchange trading.

Icahn also added to stakes in several companies he already owned. He increased his stake in ImClone by 480,000 shares. He hasn't made a decision yet to join the biotechnology company's board, according to a regulatory filing.

The company, best known for the Martha Stewart trading scandal, offered a board seat to Icahn last week after ImClone abandoned a six-month search for a buyer. Icahn, ImClone's second-biggest stockholder, raised his stake to 11.7 percent from about 10 percent, according to the filing.

He more than doubled his holdings in Cendant Corp., the New York-based travel company being broken up into four parts. At the end of the quarter, he owned 6.13 million shares, up from 2.4 million, according to the filing, or about 0.6 percent of the company.

Energy Holdings

Icahn sold several of his energy holdings, including Consol Energy Inc., the third-biggest U.S. coal producer; natural gas producer Houston Exploration Co.; and oil-and-gas company Kerr- McGee Corp. Icahn pressured the Oklahoma City-based company to divest assets last year.

He added to positions in four energy companies: Williams Cos., Pioneer Natural Resources Inc., Cimarex Energy Inc. and Transocean Inc.

To contact the reporter on this story: Katherine Burton in New York at kburton@bloomberg.net

Last Updated: August 14, 2006 17:35 EDT