30 / PRNewswire-FirstCall / -- UAL Corporation ( Nasdaq : UAUA ) , the holding company whose primary subsidiary is United Air Lines Inc . , announced today that it plans to offer , subject to market and other conditions , 19 million shares of its common stock in an underwritten registered public offering . In connection with this offering , the company intends to grant the underwriters an over-allotment option with respect to an additional 2.85 million shares of its common stock .