Passenger unit revenue, which compares ticket sales to flight capacity, fell between 5.75 percent and 6.25 percent in the fourth quarter from a year ago, United Continental Holdings Inc (UAL.N) said in a regulatory filing. The Paris attacks’ impact on demand is “concerning,” said Sterne Agee CRT analyst Adam Hackel, adding that hotel bookings were down in France during the holidays. Hackel said, however, that United’s fare hike last week by $6 round-trip may help offset the decline.