X0306 4 2019-05-28 0 0001315255 GTT Communications, Inc. GTT 0001308564 Calder Richard C/O GTT COMMUNICATIONS, INC. 7900 TYSONS ONE PLACE, SUITE 1450 MCLEAN VA 22102 1 1 0 0 President and CEO Common Stock, par value $.0001 per share 2019-05-28 4 S 0 1160 25.87 D 1332367 D Common Stock, par value $.0001 per share 495481 I By Rick Calder LLC Trust Represents shares sold to fund the employee portion of income tax withholding payable due to the vesting of shares under GTT's equity incentive plan. Such sale to fund withholding taxes is mandatory under the terms of GTT's equity incentive plan. /s/ Richard Calder 2019-05-29