Iron Mountain (NYSE: IRM) director reports 10.189 phantom stock phantom award

Rhea-AI Filing Summary

Iron Mountain Incorporated director Robin Matlock reported acquiring 10.189 phantom stock units on January 6, 2026 under the company’s Directors Deferred Compensation Plan. Each phantom share is economically equivalent to one share of Iron Mountain common stock and will be paid out in common shares on dates chosen by the director or as otherwise provided in the plan.

The 10.189 phantom shares reflect dividend equivalents, treating dividends on common stock as if they were reinvested into additional phantom shares. The weighted average reference price for this transaction was $84.625 per share, based on multiple trades between $84.304 and $84.979. Following this transaction, Matlock beneficially owns 10.189 phantom stock units directly.

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)
01/06/2026

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

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)	01/06/2026		A		10.189(2)		(1)	(1)	Common Stock	10.189	$84.625(3)	10.189	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 $84.304 to $84.979, inclusive. The Reporting Person undertakes to provide 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	01/08/2026
	** 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 IRM director Robin Matlock report?

Robin Matlock, a director of Iron Mountain Incorporated (IRM), reported the acquisition of 10.189 phantom stock units on January 6, 2026.

What are the 10.189 phantom stock units reported by IRM’s director?

The phantom stock units are bookkeeping entries that are the economic equivalent of Iron Mountain common shares and will be settled in common stock under the Directors Deferred Compensation Plan.

How were the 10.189 phantom stock units for IRM’s director calculated?

The 10.189 phantom shares reflect dividends paid on Iron Mountain common stock as if those dividends were reinvested into additional phantom shares, consistent with the plan’s terms.

At what price were the IRM phantom stock units referenced in this Form 4?

The transaction uses a weighted average price of $84.625 per share, based on multiple trades in Iron Mountain common stock between $84.304 and $84.979.

How many IRM phantom stock units does the director own after this transaction?

After this reported transaction, Robin Matlock beneficially owns 10.189 phantom stock units, held directly.

Is this IRM insider transaction a sale or an acquisition?

The Form 4 reports an acquisition (transaction code “A”) of 10.189 phantom stock units tied to Iron Mountain common stock.