[Form 4] IRON MOUNTAIN INC Insider Trading Activity

Rhea-AI Filing Summary

Robin Matlock, a director of Iron Mountain Incorporated (IRM), reported a transaction dated 10/03/2025 under a director deferred compensation arrangement. The filing shows 7.446 phantom stock units were acquired and are economically equivalent to common shares that will be payable in stock per the plan. The report lists a weighted average price of $104.422, with underlying purchase prices in the range $104.349 to $104.524. Following the transaction the Reporting Person beneficially owned 998 shares of common stock directly. The filing was signed under power of attorney on 10/07/2025.

Positive

• Director participation in deferred compensation plan shows alignment with shareholder interest via equity-linked pay
• Acquisition of 7.446 phantom shares at a weighted average price of $104.422 adds to insider ownership
• Post-transaction direct ownership of 998 common shares increases disclosed insider stake

Negative

• None.

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
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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)
10/03/2025

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

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)	10/03/2025		A		7.446(2)		(1)	(1)	Common Stock	7.446	$104.422(3)	998	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. These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

3. The price reported in Column 8 is a weighted average price. These shares of Common Stock were acquired in multiple transactions at prices ranging from $104.349 to $104.524, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock acquired at each separate price within the ranges set forth in this footnote (3).

Remarks:

	/s/ Christine Zhang, under Power of Attorney dated May 12, 2025 from Robin Matlock	10/07/2025
	** 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 did Iron Mountain director Robin Matlock report on Form 4 (IRM)?

The director reported acquiring 7.446 phantom stock units on 10/03/2025, with a weighted average price of $104.422, and now beneficially owning 998 common shares.

What are the phantom shares described in the IRM Form 4?

The phantom shares are part of the Directors Deferred Compensation Plan and are the economic equivalent of one share of common stock each; they become payable in common stock on dates selected under the Plan.

What price range was disclosed for the IRM shares acquired?

The filing discloses a weighted average price of $104.422 and states component prices ranged from $104.349 to $104.524.

When will the phantom shares convert to actual Iron Mountain common stock?

The filing says the phantom shares will become payable in common stock on various dates selected by the reporting person or as provided in the Plan; no specific conversion date is disclosed in the Form 4.

Who signed the Form 4 for Robin Matlock?

The form was signed by Christine Zhang under a Power of Attorney dated 05/12/2025, with the signature dated 10/07/2025.