X0306 4 2018-02-15 0 0001020569 IRON MOUNTAIN INC IRM 0001691591 MARSON DEBORAH C/O IRON MOUNTAIN INCORPORATED ONE FEDERAL STREET BOSTON MA 02110 0 1 0 0 EVP, General Counsel, Sec. Common Stock, par value $.01 per share 2018-02-16 4 M 0 1214 0 A 17077 D Common Stock, par value $.01 per share 2018-02-16 4 F 0 421 33.17 D 16656 D Employee Stock Option (Right to Buy) 33.72 2018-02-15 4 A 0 20741 0 A 2028-02-15 Common Stock 20741 20741 D Restricted Stock Units 2018-02-15 4 A 0 4448 0 A Common Stock 4448 4448 D Restricted Stock Units 2018-02-16 4 M 0 1214 0 D Common Stock 1214 2434 D This acquisition is reported to reflect the partial vesting of restricted stock units ("RSUs") previously granted to the Reporting Person on February 16, 2017. This stock option becomes exercisable in three substantially equal annual installments beginning on the first anniversary of the grant date. Each RSU represents a contingent right to receive one share of Iron Mountain Incorporated common stock ("Common Stock"). The RSUs 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 3,648 shares of Common Stock, were granted to the Reporting Person on February 16, 2017 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 December 7, 2016, from Deborah Marson 2018-02-20