Icahn Asks OK to Acquire 25% of USX Corp. : Takeovers: This is the third time the corporate raider has asked to increase his stake in the oil, gas and steel concern.

WASHINGTON —  Investor Carl C. Icahn disclosed Wednesday that he is requesting federal approval to acquire at least 25% of USX Corp.

In a filing with the Securities and Exchange Commission, Icahn revealed that he was seeking permission from the Federal Trade Commission to increase his stake in the Pittsburgh-based oil, gas and steel concern.

Federal Trade Commission antitrust clearance for such an acquisition is required under the Hart-Scott-Rodino Antitrust Improvements Act.

According to the SEC filing, which was released after the stock market closed, Icahn owned nearly 34 million, or 13.26%, of USX’s outstanding shares of common stock.

Icahn, known for his past corporate takeover attempts, also owns Trans World Airlines Inc.

USX finished down 12.5 cents at $33.625 in New York Stock Exchange trading Wednesday.

The SEC document noted that last November, Icahn made a Hart-Scott-Rodino filing indicating his intention to acquire more than 15% of USX’s voting securities “and, depending upon market conditions, more than 25%” of its voting securities.

But because his group did not acquire in excess of 15% within a year, a new filing is required to permit acquisition above 15%, said the filing, known as a 13-D.

USX spokesman William Kessler said the company was aware of Icahn’s filing but had no comment.

He said Icahn made similar requests in late 1987 and late 1988 but never boosted his stake to the amount requested within the allotted year. “This is the third time he’s filed,” Kessler said. “This is a renewable thing.”