Mega corporate travel agency air transactions processed through ARC in December fell by about 4.6 percent year over year, the sharpest monthly decline of 2011.

Including American Express, BCD Travel, Carlson Wagonlit Travel, HRG and Omega World Travel, the mega agency category in December performed better than the "online" category, for which transactions declined more than 9 percent year over year, but worse than the "other" category, for which ARC recorded 0.3 percent growth.