United Airlines reduced its quarterly loss to $434 million and posted surprisingly strong revenue as U.S. vacation travel picked up. In reporting its second-quarter results Tuesday, the Chicago-based airline said it expects to earn a pretax profit in the remaining two quarters of the year. That would break a string of six-straight money-losing quarters since the pandemic began to crush air travel. “Our airline has reached a meaningful turning point: We’re expecting to be back to making a profit once again,” CEO Scott Kirby said in a prepared statement. However, United is trailing key rivals as the airlines claw to get back to profitability. In April, Southwest was the first U.S. airline to report a profit since the pandemic hit, and Delta followed last week—in both cases, profits were possible only because of money from taxpayers. United’s shares rose 6.6 percent in regular trading Tuesday as travel stocks rebounded from …