X0306 4 2017-11-30 0000354190 GALLAGHER ARTHUR J & CO AJG 0001186002 DURKIN JAMES W JR 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 Vice President Common Stock 2017-11-30 4 M 0 403 0 A 303720.1376 D Common Stock 2017-11-30 4 F 0 403 65.63 D 303317.1376 D Phantom Stock 2017-11-30 4 M 0 403 0 D Common Stock 403 187515 D Each share of phantom stock represents a right to receive one share of Gallagher common stock. These shares represent awards under the Age 62 Plan, a nonqualified deferred compensation plan of the Company, which have been deemed invested in Company common stock at the election of the reporting person. Participants vest in these awards when they attain age 62, or after a one-year period for participants who have attained age 61. This report is being filed to reflect an accelerated distribution under the Age 62 Plan to cover applicable taxes in connection with a vesting event. /s/ April Hanes-Dowd, by power of attorney 2017-12-04