Iron Mountain GC reports RSU vesting, tax withholding

Iron Mountain Inc. executive Michelle Vervais Altamura, EVP, General Counsel and Secretary, reported several equity transactions dated March 1, 2026.

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Rhea-AI Filing Summary

Iron Mountain Inc. executive Michelle Vervais Altamura, EVP, General Counsel and Secretary, reported several equity transactions dated March 1, 2026. The filing shows multiple tranches of restricted stock units (RSUs) vesting that were originally granted in 2023, 2024 and 2025, with each RSU representing a right to receive one share of common stock.

Upon vesting, corresponding shares of Iron Mountain common stock were issued to her. The company then withheld portions of these shares at a price of $108.33 per share to satisfy income tax withholding obligations related to the RSU net settlement, and the filing specifies that these withholdings do not represent open‑market sales.

Insider Trade Summary

2,963 shares exercised/converted

Exercise 9 txns

Insider Altamura Michelle Vervais

Role EVP, General Counsel, Sec.

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	1,458	$0.00	$0.00
Exercise	Restricted Stock Units	432	$0.00	$0.00
Exercise	Restricted Stock Units	1,073	$0.00	$0.00
Exercise	Common Stock, par value $.01 per share	1,458	$0.00	$0.00
Exercise Price or Tax Liability	Common Stock, par value $.01 per share	486	$108.33	$53K
Exercise	Common Stock, par value $.01 per share	432	$0.00	$0.00
Exercise Price or Tax Liability	Common Stock, par value $.01 per share	144	$108.33	$16K
Exercise	Common Stock, par value $.01 per share	1,073	$0.00	$0.00
Exercise Price or Tax Liability	Common Stock, par value $.01 per share	357	$108.33	$39K

Holdings After Transaction: Restricted Stock Units — 2,578 contracts (Direct); Common Stock, par value $.01 per share — 7,728 shares (Direct)

Footnotes (8)

F1. This acquisition is reported to reflect the full vesting of restricted stock units ("RSUs") previously granted to the Reporting Person on March 1, 2023.
F2. 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 RSUs and does not represent a sale.
F3. This acquisition is reported to reflect the partial vesting of RSUs previously granted to the Reporting Person on March 1, 2024.
F4. This acquisition is reported to reflect the partial vesting of RSUs previously granted to the Reporting Person on March 1, 2025.
F5. Each RSU represents a contingent right to receive one share of Common Stock.
F6. The RSUs, representing a contingent right to receive a total of 4,374 shares of Common Stock, were granted to the Reporting Person on March 1, 2023 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.
F7. The RSUs, representing a contingent right to receive a total of 1,295 shares of Common Stock, were granted to the Reporting Person on March 1, 2024 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.
F8. The RSUs, representing a contingent right to receive a total of 3,219 shares of Common Stock, were granted to the Reporting Person on March 1, 2025 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.

FAQ

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What did Iron Mountain (IRM) executive Michelle Vervais Altamura report in this Form 4?

She reported RSU vesting and related share issuances. Several restricted stock unit grants from 2023, 2024 and 2025 vested, each converting into one share of Iron Mountain common stock, reflecting ongoing equity compensation rather than discretionary market purchases or sales.

Were any of Michelle Vervais Altamura’s Iron Mountain (IRM) transactions open-market stock sales?

No, the filing describes tax-withholding dispositions only. Shares of common stock were withheld by Iron Mountain at $108.33 per share to cover income tax obligations from RSU vesting, and the document explicitly states these withheld shares do not represent a sale.

How do the RSUs reported by Iron Mountain (IRM) convert into common stock for the executive?

Each RSU represents a contingent right to receive one share of common stock. The grants from 2023, 2024 and 2025 vest in three substantially equal annual installments, and vested units are settled in Iron Mountain common stock on the applicable vesting dates.

What RSU grant schedules are disclosed for Iron Mountain (IRM) executive equity awards?

The filing notes 4,374 RSUs granted in 2023, 1,295 in 2024 and 3,219 in 2025. Each grant vests in three substantially equal annual installments beginning on the first anniversary of its March 1 grant date, providing multi-year, time-based equity compensation.

What role does Michelle Vervais Altamura hold at Iron Mountain (IRM) in this Form 4?

She is listed as Executive Vice President, General Counsel and Secretary. The transactions reflect equity compensation tied to her leadership role, including vesting of restricted stock units and associated share issuances, alongside share withholdings to satisfy income tax obligations.

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Form 4 Insider Transactions: What Each Field Means →

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Accepted by SEC EDGAR 03/03/2026 - 07:21 PM EST

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^*

Altamura Michelle Vervais

(Last)

(First)

(Middle)

C/O IRON MOUNTAIN INCORPORATED

85 NEW HAMPSHIRE AVE, SUITE 150

(Street)

PORTSMOUTH

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, General Counsel, Sec.

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock, par value $.01 per share	03/01/2026		M		1,458⁽¹⁾	A	$0	7,210	D
Common Stock, par value $.01 per share	03/01/2026		F		486⁽²⁾	D	$108.33	6,724	D
Common Stock, par value $.01 per share	03/01/2026		M		432⁽³⁾	A	$0	7,156	D
Common Stock, par value $.01 per share	03/01/2026		F		144⁽²⁾	D	$108.33	7,012	D
Common Stock, par value $.01 per share	03/01/2026		M		1,073⁽⁴⁾	A	$0	8,085	D
Common Stock, par value $.01 per share	03/01/2026		F		357⁽²⁾	D	$108.33	7,728	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Restricted Stock Units	⁽⁵⁾	03/01/2026		M			1,458	⁽⁶⁾	⁽⁶⁾	Common Stock, par value $.01 per share	1,458	$0	0	D
Restricted Stock Units	⁽⁵⁾	03/01/2026		M			432	⁽⁷⁾	⁽⁷⁾	Common Stock, par value $.01 per share	432	$0	432	D
Restricted Stock Units	⁽⁵⁾	03/01/2026		M			1,073	⁽⁸⁾	⁽⁸⁾	Common Stock, par value $.01 per share	1,073	$0	2,146	D

Explanation of Responses:

1. This acquisition is reported to reflect the full vesting of restricted stock units ("RSUs") previously granted to the Reporting Person on March 1, 2023.

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 RSUs and does not represent a sale.

3. This acquisition is reported to reflect the partial vesting of RSUs previously granted to the Reporting Person on March 1, 2024.

4. This acquisition is reported to reflect the partial vesting of RSUs previously granted to the Reporting Person on March 1, 2025.

5. Each RSU represents a contingent right to receive one share of Common Stock.

6. The RSUs, representing a contingent right to receive a total of 4,374 shares of Common Stock, were granted to the Reporting Person on March 1, 2023 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.

7. The RSUs, representing a contingent right to receive a total of 1,295 shares of Common Stock, were granted to the Reporting Person on March 1, 2024 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.

8. The RSUs, representing a contingent right to receive a total of 3,219 shares of Common Stock, were granted to the Reporting Person on March 1, 2025 and vest in three substantially equal annual installments beginning on the first anniversary of the grant date.

Remarks:

	/s/ Christine Zhang, under Power of Attorney dated September 17, 2024, from Michelle Altamura	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.

Source: View Original Filing on SEC EDGAR