Iron Mountain (NYSE: IRM) EVP sells shares, settles performance units

Rhea-AI Filing Summary

IRON MOUNTAIN INC executive Mark Kidd, EVP and GM of Data Centers & Asset Lifecycle Management, reported multiple equity transactions. On March 1, 2026, previously granted performance units fully vested and were exercised into 149,768 shares of common stock at a stated price of $0.0000 per share, reflecting the Compensation Committee’s award determination after the performance period.

To cover income tax withholding from this vesting, 61,342 common shares were withheld by Iron Mountain at a price of $108.33 per share, which the company specifies does not represent a sale. On March 2, 2026, Kidd executed an open-market sale of 6,000 common shares at $107.27 per share under a pre-established Rule 10b5‑1 trading plan adopted on March 20, 2025. After these transactions, he directly owns 131,507 common shares.

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

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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).

X

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^*

Kidd Mark

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, GM Data Centers & ALM

3. Date of Earliest Transaction (Month/Day/Year)
03/01/2026

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	03/01/2026		M		149,768(1)	A	$0	198,849	D
Common Stock, par value $.01 per share	03/01/2026		F		61,342(2)	D	$108.33	137,507	D
Common Stock, par value $.01 per share	03/02/2026		S(3)		6,000	D	$107.27	131,507	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
Performance Units	(4)	03/01/2026		M			149,768	(5)	(5)	Common Stock, par value $.01 per share	149,768	$0	0	D

Explanation of Responses:

1. This acquisition is reported to reflect the full vesting of performance units ("PUs") previously granted to the Reporting Person on March 1, 2023. Effective February 16, 2026, the Compensation Committee of Iron Mountain Incorporated's Board of Directors determined the actual award of PUs under the grant after completion of the relevant performance period, and the PUs fully vested on March 1, 2026.

2. Represents the number of shares of Common Stock that have been withheld by the Issuer to satisfy its income tax withholding obligation in connection with the net settlement of the PUs and does not represent a sale.

3. The transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 20, 2025.

4. Each PU represents a contingent right to receive one share of Iron Mountain Incorporated common stock ("Common Stock").

5. The PUs were initially granted to the Reporting Person on March 1, 2023. Effective as of February 16, 2026, the Compensation Committee determined the actual award of PUs under the grant after completion of the relevant performance period, and the PUs fully vested on March 1, 2026.

Remarks:

	/s/ Christine Zhang, under Power of Attorney dated June 19, 2025, from Mark Kidd	03/03/2026
	** 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 equity awards vested for IRM executive Mark Kidd in this Form 4?

Mark Kidd had performance units fully vest into 149,768 Iron Mountain common shares. The award related to units granted on March 1, 2023, with the Compensation Committee determining the actual award on February 16, 2026, after the performance period ended.

How many Iron Mountain (IRM) shares did Mark Kidd sell in this filing?

Mark Kidd sold 6,000 shares of Iron Mountain common stock in an open-market transaction. The sale occurred on March 2, 2026, at a price of $107.27 per share, and was executed under a pre-arranged Rule 10b5-1 trading plan.

What does the tax withholding transaction mean in the IRM Form 4 for Mark Kidd?

The Form 4 shows 61,342 Iron Mountain shares were withheld to satisfy income tax obligations from the performance unit vesting. The company states this withholding is not a sale, but rather shares retained by the issuer to cover associated tax liabilities.

How many Iron Mountain (IRM) shares does Mark Kidd own after these transactions?

After the reported transactions, Mark Kidd directly owns 131,507 shares of Iron Mountain common stock. This balance reflects the vesting and exercise of performance units, the related tax withholding, and the separate open-market sale of 6,000 shares.

Was Mark Kidd’s sale of Iron Mountain shares part of a Rule 10b5-1 plan?

Yes. The Form 4 states the 6,000-share open-market sale was made under a Rule 10b5-1 trading plan. That plan was adopted on March 20, 2025, allowing pre-scheduled trades regardless of later possession of material nonpublic information.

What is the relationship between Mark Kidd’s performance units and Iron Mountain common stock?

Each performance unit represents a contingent right to receive one Iron Mountain common share. Upon full vesting and award determination, the units converted into common stock on a one-for-one basis, creating the 149,768-share acquisition reported in the Form 4.