Order Reprints Text size Passengers waiting at the Southwest Airlines counter at Ronald Reagan Washington National Airport. Daniel Slim/AFP via Getty Images Investors who buy airline stocks may now have to endure some pain and take a “leap of faith” that revenues will recover sharply in the second half of the year, one analyst says. Airlines came into the new year with high hopes of sustaining some momentum from December, when air traffic soared around the holidays—reaching highs not seen since the pandemic started. Yet booking trends have since weakened, with the virus surging to record highs around the U.S. and taking a toll on travel demand.