IRON MOUNTAIN INC

(Zip Code)

(617)535-4766

(Registrant’s Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities Registered Pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.07. Submission of Matters to a Vote of Security Holders.

The Annual Meeting of Stockholders of Iron Mountain Incorporated (the "Company") was held on May 7, 2026 (the "Annual Meeting"). At the Annual Meeting, the Company’s stockholders elected eleven directors, each for a one-year term of office to serve until the Company’s 2027 Annual Meeting of Stockholders, or until their successors are elected and qualified. The nominated directors received the following votes:

At the Annual Meeting, the Company’s stockholders approved a non-binding advisory resolution on the compensation paid to the Company’s named executive officers as disclosed pursuant to Item 402 of Regulation S-K in the Proxy Statement. This proposal received the following votes: