Online travel agencies have a tremendous marketing edge over leisure agencies, and corporate travel agencies might be feeling the pinch of macro uncertainties.

U.S. travel agency sales of airline tickets fell 5% overall in May, according to new data from the Airlines Reporting Corp. (ARC). But while total sales declined, online travel agencies bucked the trend with growing flight bookings.

ARC, which tracks U.S. travel agency transactions, reported Wednesday that online travel agency (OTA) sales rose 8% year over year last month. Meanwhile, flight sales through traditional leisure agencies dropped 5%, and corporate tra