[Form 4] IRON MOUNTAIN INC Insider Trading Activity

Rhea-AI Filing Summary

Iron Mountain Incorporated director reports stock conversion under a deferred compensation plan. On 01/02/2026, the reporting person acquired 998 shares of Iron Mountain common stock at a price of $0 per share through the exercise of phantom stock units. After this transaction, the reporting person beneficially owned 28,549 shares of common stock in direct form.

The derivative position in 998 phantom stock units was reduced to zero as they were settled in common stock. Each phantom share was economically equivalent to one share of common stock, and settlement occurs in stock under the company’s Directors Deferred Compensation Plan, according to the reporting person’s elections and plan terms.

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 NH 03801

(City) (State) (Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
01/02/2026

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

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

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

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	01/02/2026		M		998	A	$0	28,549	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
Phantom Stock	(1)	01/02/2026		M			998(2)	(1)	(1)	Common Stock	998	$0	0	D

Explanation of Responses:

1. Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each Phantom Share is the economic equivalent of one share of Common Stock.

2. Settlement of the Phantom Shares is in Common Stock.

Remarks:

	/s/ Christine Zhang, under Power of Attorney dated May 12, 2025 from Robin Matlock	01/06/2026
	** 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.

FAQ

What insider transaction did IRON MOUNTAIN INC (IRM) report?

The filing reports that a director acquired 998 shares of Iron Mountain common stock on 01/02/2026 by settling phantom stock units under a deferred compensation plan.

At what price were the IRM shares acquired in this Form 4 filing?

The 998 shares of Iron Mountain common stock were acquired at a stated price of $0 per share, reflecting settlement of phantom stock rather than an open-market purchase.

How many IRON MOUNTAIN INC (IRM) shares does the director own after the transaction?

Following the reported transaction, the director beneficially owned 28,549 shares of Iron Mountain common stock in direct ownership.

What happened to the phantom stock units reported by the IRM director?

The director’s 998 phantom stock units were settled and converted into 998 shares of Iron Mountain common stock, reducing the reported phantom stock balance to 0 derivative securities.

What is the Iron Mountain Directors Deferred Compensation Plan mentioned in the filing?

The filing explains that under the Iron Mountain Incorporated Directors Deferred Compensation Plan, phantom stock units are payable in common stock on dates selected by the director or as otherwise provided in the plan.

What does each phantom share represent for IRON MOUNTAIN INC (IRM)?

Each phantom share is described as the economic equivalent of one share of Iron Mountain common stock, with settlement occurring in common stock.