Alaska Air Group's (ALK) proposed acquisition of Hawaiian Airlines parent Hawaiian Holdings (HA) has cleared the U.S. Department of Justice after the period for its regulatory investigation expired yesterday. Hawaiian Holdings' stock has responded to the news by jumping more than 11% in Tuesday's session, while ALK shares are down slightly at last check."This is a significant milestone in the process to join our airlines," Alaska Air Group said in a statement. The air carrier added that during the Departmen ...