X0508 4 2026-02-16 0 0001020569 IRON MOUNTAIN INC IRM 0001720656 Borges Daniel C/O IRON MOUNTAIN INCORPORATED 85 NEW HAMPSHIRE AVENUE, SUITE 150 PORTSMOUTH NH 03801 0 1 0 0 SVP & Chief Accounting Officer 0 Performance Units 2026-02-16 4 A 0 6537 0 A Common Stock, par value $.01 per share 6537 9152 D Each Performance Unit ("PU") represents a contingent right to receive one share of Iron Mountain Incorporated common stock ("Common Stock"). The PUs were initially granted to the Reporting Person on March 1, 2023. This Form 4 is being filed to reflect the determination by the Compensation Committee, effective as of February 16, 2026, of the actual award of PUs under the grant after completion of the relevant performance period. The PU were initially granted to the Reporting Person on March 1, 2023, and will fully vest on March 1, 2026. /s/ Christine Zhang, under Power of Attorney dated June 19, 2025 from Daniel Borges 2026-02-18