Iron Mountain (IRM)

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-05-07 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: IRON MOUNTAIN INC (IRM) CIK: 0001020569 --- Reporting Owner --- Name: Samuels Theodore R. II CIK: 0001688276 Role: Director --- Derivative Transactions --- [Transaction #1] Security: Phantom Stock Date: 2026-05-07 | Code: A (Grant or award) Shares: +1,892 | Price: $0.00 Shares Owned After: 13,390.41 | Ownership: D (Direct) Footnotes: [F1] Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan ("DDCP"), the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of Common Stock. [F2] Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest in their entirety on the grant date. The Reporting Person has elected that upon vesting of RSUs, receipt of the shares of Common Stock be deferred under the DDCP; accordingly, upon vesting, the Reporting Person will instead receive an equal number of Phantom Shares. [F1] Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan ("DDCP"), the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of Common Stock. [F1] Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan ("DDCP"), the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of Common Stock. --- Footnotes (Complete Index) --- F1: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan ("DDCP"), the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of Common Stock. F2: Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest in their entirety on the grant date. The Reporting Person has elected that upon vesting of RSUs, receipt of the shares of Common Stock be deferred under the DDCP; accordingly, upon vesting, the Reporting Person will instead receive an equal number of Phantom Shares. --- Signature --- /s/ /s/ Keely Stewart, under Power of Attorney dated July 6, 2023 from Theodore R Samuels (2026-05-11)