X0306 4 2017-02-21 0 0001020569 IRON MOUNTAIN INC IRM 0001291613 Cloutier Ernest W C/O IRON MOUNTAIN INCORPORATED ONE FEDERAL STREET BOSTON MA 02110 0 1 0 0 EVP Common Stock, par value $.01 per share 2017-02-21 4 M 0 1801 0 A 41905 D Common Stock, par value $.01 per share 2017-02-21 4 F 0 584 37.71 D 41321 D Common Stock, par value $.01 per share 2017-02-21 4 M 0 2388 0 A 43709 D Common Stock, par value $.01 per share 2017-02-21 4 F 0 760 37.71 D 42949 D Restricted Stock Units 2017-02-21 4 M 0 1801 0 D Common Stock 1801 1807 D Restricted Stock Units 2017-02-21 4 M 0 2388 0 D Common Stock 2388 4786 D This acquisition is reported to reflect the partial vesting of restricted stock units ("RSUs") previously granted to the Reporting Person on February 19, 2015. This acquisition is reported to reflect the partial vesting of RSUs previously granted to the Reporting Person on February 18, 2016. Each RSU represents a contingent right to receive one share of Iron Mountain Incorporated common stock ("Common Stock"). The RSUs, representing a contingent right to receive a total of 5,408 shares of Common Stock, were granted to the Reporting Person on February 19, 2015 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date. The RSUs, representing a contingent right to receive a total of 7,174 shares of Common Stock, were granted to the Reporting Person on February 18, 2016 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date. /s/ Elizabeth Tammaro, under Power of Attorney dated May 26, 2016, from Ernest W. Cloutier 2017-02-23