TWA <TWA> CONFIRMS OWNERSHIP OF USAIR <U> STOCK Trans World Airlines Inc said it owns more than four mln USAir Group shares or about 15 pct of the total outstanding. TWA said it may acquire additional shares in the open market, in private transactions, through a tender offer or otherwise, subject to Department of Transportation approval. TWA has offered 52 dlrs per share for USAir Group. USAir rejected the offer yesterday, calling it a last-minute attempt to interfere with its takeover of Piedmont Aviation Inc. A TWA spokesman said the company has filed an application for approval on its offer to buy USAir with the Department of Transportation, and later today it will file a response to USAir's motion with the DOT to dismiss the TWA application. TWA said it made the statement today on its stock position in USAir in response to inquiries. Traders said they believed TWA Chairman Carl Icahn was the buyer of an 855,000 share block crossed today by Salomon Brothers. USAir stock was trading at 50-3/4, up 2-1/4 on heavy volume of 3.1 mln shares. TWA stock fell 3/8 to 30-5/8. While analysts and arbitragers have speculated that Icahn may have made the offer for USAir in order to trigger the acquisition of his own airline, Wall Street today began to take Icahn's effort more seriously. "I think he's going to be the next Frank Lorenzo of Wall Street," said one market source. Lorenzo, chairman of Texas Air, has added to his airline with the acquisitions of Eastern Airlines and People Express Airlines. There was also speculation that Icahn would like to buy USAir and then sell TWA as a merged company.