X0508 4 2026-01-02 0 0001020569 IRON MOUNTAIN INC IRM 0002039171 Altamura Michelle Vervais C/O IRON MOUNTAIN INCORPORATED 85 NEW HAMPSHIRE AVE, SUITE 150 PORTSMOUTH NH 03801 0 1 0 0 EVP, General Counsel, Sec. 0 Common Stock, par value $.01 per share 2026-01-02 4 M 0 1214 0 A 6221 D Common Stock, par value $.01 per share 2026-01-02 4 F 0 469 83.24 D 5752 D Restricted Stock Units 2026-01-02 4 M 0 1214 0 D Common Stock, par value $.01 per share 1214 1214 D This acquisition is reported to reflect the partial vesting of restricted stock units ("RSUs") previously granted to the Reporting Person on January 2, 2024. Each RSU represents a contingent right to receive one share of Common Stock. The RSUs, representing a contingent right to receive a total of 3,642 shares of Common Stock, were granted to the Reporting Person on January 2, 2024 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date. /s/ Christine Zhang, under Power of Attorney dated September 17, 2024, from Michelle Altamura 2026-01-06