Iron Mountain (IRM) director Robin Matlock granted 1,892 RSU-settled shares

Rhea-AI Filing Summary

Matlock Robin reported acquisition or exercise transactions in this Form 4 filing.

IRON MOUNTAIN INC director Robin Matlock received a stock-based award of 1,892 common shares on May 7, 2026. The shares were granted as restricted stock units that vested in full on the grant date, effectively delivering the shares immediately at no cash cost. Following this grant, Matlock’s directly held position increased to 30,451.189 common shares, reflecting routine equity compensation rather than an open-market purchase or sale.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Matlock Robin

Role null

Type	Security	Shares	Price	Value
Grant/Award	Common Stock, par value $.01 per share	1,892	$0.00	--

Holdings After Transaction: Common Stock, par value $.01 per share — 30,451.189 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Shares acquired via RSU grant: 1,892 shares Price per share for award: $0.00 per share Total shares held after transaction: 30,451.189 shares +2 more

5 metrics

Shares acquired via RSU grant 1,892 shares Restricted stock units granted and vested on May 7, 2026

Price per share for award $0.00 per share Reported transaction price for the RSU-settled share grant

Total shares held after transaction 30,451.189 shares Director’s direct ownership following the May 7, 2026 grant

Transaction code A Classified as grant, award, or other acquisition of common stock

Transaction direction acquire Non-derivative equity award increasing direct holdings

Key Terms

restricted stock units ("RSUs"), vest in their entirety, grant, award, or other acquisition, Common Stock, par value $.01 per share

4 terms

restricted stock units ("RSUs") financial

"Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 7, 2026."

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

vest in their entirety financial

"The RSUs vest in their entirety on the grant date."

grant, award, or other acquisition regulatory

"transaction_code_description: Grant, award, or other acquisition"

Common Stock, par value $.01 per share financial

"security_title: Common Stock, par value $.01 per share"

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Matlock Robin

(Last) (First) (Middle)

C/O IRON MOUNTAIN INCORPORATED

85 NEW HAMPSHIRE AVENUE, SUITE 150

(Street)

PORTSMOUTH NEW HAMPSHIRE 03801

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
IRON MOUNTAIN INC [ IRM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/07/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock, par value $.01 per share	05/07/2026		A		1,892(1)	A	$0	30,451.189	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 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.

Remarks:

	/s/ Christine Zhang, under Power of Attorney dated May 12, 2025 from Robin Matlock	05/11/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What did IRON MOUNTAIN INC (IRM) director Robin Matlock report on this Form 4?

Robin Matlock reported receiving 1,892 shares of IRON MOUNTAIN INC common stock as an equity award. The grant came through restricted stock units that settled in shares and vested in full on the May 7, 2026 grant date.

How many IRON MOUNTAIN INC shares did Robin Matlock acquire in this transaction?

Matlock acquired 1,892 shares of IRON MOUNTAIN INC common stock through a restricted stock unit grant. These shares were issued upon settlement of the RSUs, which vested immediately on the grant date, increasing Matlock’s direct ownership accordingly.

Was the IRON MOUNTAIN INC Form 4 transaction an open-market buy or sell?

The transaction was not an open-market buy or sell; it was an equity award. Robin Matlock received 1,892 shares via a restricted stock unit grant that vested in full on the grant date, with no price paid per share reported.

What is Robin Matlock’s IRON MOUNTAIN INC share ownership after this RSU grant?

After the restricted stock unit grant settled, Matlock directly holds 30,451.189 shares of IRON MOUNTAIN INC common stock. This total reflects the addition of the 1,892 shares from the May 7, 2026 award transaction reported on the Form 4.

How were the IRON MOUNTAIN INC restricted stock units structured in this filing?

The filing states the award consists of shares issuable upon settlement of restricted stock units granted May 7, 2026. According to the footnote, the RSUs vest in their entirety on the grant date, meaning the full award became share-settled immediately.