Debt (Tables)

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Schedule of Carrying Amount and Fair Value of Long-term Debt Instruments

Long-term debt is as follows:

	DECEMBER 31, 2025								DECEMBER 31, 2024
	DEBT (INCLUSIVE OF DISCOUNT)		UNAMORTIZED DEFERRED FINANCING COSTS		CARRYING AMOUNT		FAIR VALUE		DEBT (INCLUSIVE OF DISCOUNT)		UNAMORTIZED DEFERRED FINANCING COSTS		CARRYING AMOUNT		FAIR VALUE
Revolving Credit Facility(1)	$	751,500	$	(8,207)	$	743,293	$	751,500	$	121,000	$	(9,253)	$	111,747	$	121,000
Term Loan A(1)	487,500		—		487,500		487,500		216,016		—		216,016		216,016
Term Loan B(1)(2)	2,020,957		(12,465)		2,008,492		2,031,495		1,840,181		(14,690)		1,825,491		1,850,698
Virginia 3 Term Loans(3)	271,079		(1,189)		269,890		271,079		271,079		(3,013)		268,066		271,079
Virginia 4/5 Term Loans due 2025(3)	—		—		—		—		76,535		(2,752)		73,783		76,535
Virginia 6 Term Loans(3)	210,000		(2,633)		207,367		210,000		137,495		(4,605)		132,890		137,495
Virginia 7 Term Loans(3)	275,314		(4,351)		270,963		275,314		32,074		(7,591)		24,483		32,074
Virginia 4/5 Term Loans due 2030(5)	208,224		(3,529)		204,695		208,224		—		—		—		—
Australian Dollar Term Loan(3)(4)	262,192		(1,965)		260,227		263,948		175,813		(265)		175,548		176,655
UK Revolving Credit Facility(3)	188,385		(2,002)		186,383		188,385		175,503		(1,034)		174,469		175,503
37/8% GBP Senior Notes due 2025 (the "GBP Notes")(5)(6)(7)	—		—		—		—		501,437		(789)		500,648		490,155
47/8% Senior Notes due 2027 (the “47/8% Notes due 2027")(5)(6)(8)	1,000,000		(2,488)		997,512		995,000		1,000,000		(3,910)		996,090		972,500
51/4% Senior Notes due 2028 (the “51/4% Notes due 2028")(5)(6)(8)	825,000		(2,657)		822,343		823,969		825,000		(3,838)		821,162		804,375
5% Senior Notes due 2028 (the “5% Notes due 2028")(5)(6)(8)	500,000		(1,869)		498,131		497,500		500,000		(2,592)		497,408		481,250
7% Senior Notes due 2029 (the "7% Notes")(5)(6)(8)	1,000,000		(6,559)		993,441		1,025,000		1,000,000		(8,686)		991,314		1,020,000
47/8% Senior Notes due 2029 (the “47/8% Notes due 2029")(5)(6)(8)	1,000,000		(5,425)		994,575		983,750		1,000,000		(6,871)		993,129		945,000
51/4% Senior Notes due 2030 (the “51/4% Notes due 2030")(5)(6)(8)	1,300,000		(6,894)		1,293,106		1,280,500		1,300,000		(8,399)		1,291,601		1,235,000
41/2% Senior Notes due 2031 (the “41/2% Notes")(5)(6)(8)	1,100,000		(6,430)		1,093,570		1,042,250		1,100,000		(7,674)		1,092,326		1,001,000
5% Senior Notes due 2032 (the “5% Notes due 2032")(5)(6)(9)	750,000		(8,595)		741,405		710,625		750,000		(9,900)		740,100		688,125
55/8% Senior Notes due 2032 (the “55/8% Notes")(5)(6)(8)	600,000		(3,823)		596,177		586,500		600,000		(4,404)		595,596		570,000
61/4% Senior Notes due 2033 (the “61/4% Notes")(5)(6)(8)	1,200,000		(12,752)		1,187,248		1,206,000		1,200,000		(14,517)		1,185,483		1,194,000
43/4% Euro Senior Notes due 2034 (the "Euro Notes")(5)(6)(8)	1,408,825		(16,765)		1,392,060		1,370,082		—		—		—		—
Real Estate Mortgages, Financing Lease Liabilities and Other(10)	785,497		(1,512)		783,985		785,497		614,231		(1,825)		612,406		614,231
Accounts Receivable Securitization Program(3)(11)	400,000		(404)		399,596		400,000		400,000		(670)		399,330		400,000
Total Long-term Debt	16,544,473		(112,514)		16,431,959				13,836,364		(117,278)		13,719,086
Less Current Portion	(216,074)		—		(216,074)				(715,109)		—		(715,109)
Long-term Debt, Net of Current Portion	$	16,328,399	$	(112,514)	$	16,215,885			$	13,121,255	$	(117,278)	$	13,003,977

(1)The capital stock or other equity interests of our United States subsidiaries representing the substantial majority of our United States operations, and up to 66% of the capital stock or other equity interests of most of our first-tier foreign subsidiaries, are pledged to secure these debt instruments, together with all intercompany obligations (including promissory notes) of subsidiaries owed to us or to one of our United States subsidiary guarantors. In addition, Iron Mountain Canada Operations ULC has pledged 66% of the capital stock of its subsidiaries, and all intercompany obligations (including promissory notes) owed to or held by it, to secure the Revolving Credit Facility. The fair value (Level 2 and Level 3 of fair value hierarchy described at Note 2.p.) of these debt instruments approximates the carrying value, as borrowings under these debt instruments are based on current variable market interest rates (plus a margin that is subject to change based on our consolidated leverage ratio), as of December 31, 2025 and 2024 (collectively, the "Credit Agreement Collateral").

(2)The amount of debt for the Term Loan B (as defined below) reflects an unamortized original issue discount of $10,538 and $10,517 as of December 31, 2025 and 2024, respectively.

(3)The fair value (Level 2 of fair value hierarchy described at Note 2.p.) of this debt instrument approximates the carrying value as borrowings under this debt instrument are based on a current variable market interest rate.

(4)The amount of debt for the AUD Term Loan (as defined below) reflects an unamortized original issue discount of $1,756 and $842 as of December 31, 2025 and 2024, respectively.

(5)The fair values (Level 2 of fair value hierarchy described at Note 2.p.) of these debt instruments are based on quoted market prices for comparable notes on December 31, 2025 and 2024, respectively.

(6)Collectively, the "Unregistered Notes". The Unregistered Notes have not been registered under the Securities Act of 1933, as amended (the "Securities Act"), or under the securities laws of any other jurisdiction. Unless they are registered, the Unregistered Notes may be offered only in transactions that are exempt from registration under the Securities Act or the securities laws of any other jurisdiction.

(7)Iron Mountain (UK) PLC ("IM UK") is the direct obligor on the GBP Notes, which are fully and unconditionally guaranteed, on a senior basis, by IMI and IMI’s United States subsidiaries that represent the substantial majority of our United States operations (the "Note Guarantors"). These guarantees are joint and several obligations of IMI and the Note Guarantors. The remainder of our subsidiaries do not guarantee the GBP Notes. The full amount of the GBP Notes is classified within the current portion of long-term debt in our Consolidated Balance Sheet at December 31, 2024.

(8)Collectively, the "Parent Notes". IMI is the direct obligor on the Parent Notes, which are fully and unconditionally guaranteed, on a senior basis, by the Note Guarantors. These guarantees are joint and several obligations of the Note Guarantors. The remainder of our subsidiaries do not guarantee the Parent Notes.

(9)Iron Mountain Information Management Services, Inc. ("IMIM Services") is the direct obligor on the 5% Notes due 2032, which are fully and unconditionally guaranteed, on a senior basis, by IMI and the Note Guarantors. These guarantees are joint and several obligations of IMI and the Note Guarantors. The remainder of our subsidiaries do not guarantee the 5% Notes due 2032.

(10)We believe the fair value (Level 2 of fair value hierarchy described at Note 2.p.) of this debt approximates its carrying value as these borrowings are based on current market interest rates. This debt includes the following:

	DECEMBER 31, 2025		DECEMBER 31, 2024
Real estate mortgages(1)	$	73,250	$	74,250
Financing lease liabilities(2)	527,199		406,841
Other notes and other obligations(3)	185,048		133,140
	$	785,497	$	614,231

(1)Bear interest at approximately 4.2% and 4.4% at December 31, 2025 and 2024, respectively, and includes $50,000 outstanding under our Mortgage Securitization Program at both December 31, 2025 and 2024.

(2)Bear a weighted average interest rate of 5.6% and 5.2% at December 31, 2025 and 2024, respectively.

(3)These notes and other obligations, which were assumed by us as a result of certain acquisitions, bear a weighted average interest rate of 6.5% and 7.2% at December 31, 2025 and 2024, respectively.

(11) The Accounts Receivable Securitization Special Purpose Subsidiaries (as defined below) are the obligors under this program.

These agreements primarily consist of term loan facilities with the following terms:

AGREEMENT	MAXIMUM BORROWING AMOUNT		OUTSTANDING BORROWINGS AS OF DECEMBER 31, 2025		DIRECT OBLIGOR	CONTRACTUAL INTEREST RATE	UNUSED COMMITMENT FEE		MATURITY DATE(1)
Virginia 3 Term Loans(2)	$	275,000	$	271,079	Iron Mountain Data Centers Virginia 3, LLC	SOFR plus 2.50%	0.75	%	August 31, 2026
Virginia 7 Term Loans(3)	300,000		275,314		Iron Mountain Data Centers Virginia 7, LLC	SOFR plus 2.50%	0.75	%	April 12, 2027
Virginia 6 Term Loans(4)	210,000		210,000		Iron Mountain Data Centers Virginia 6, LLC	SOFR plus 2.75%	0.75	%	May 3, 2027
Virginia 4/5 Term Loans due 2030(5)	208,224		208,224		Iron Mountain Data Centers Virginia 4/5 Subsidiary, LLC	5.60%	N/A		November 1, 2030

(1)All obligations will become due on the specified maturity dates. Each agreement, with the exception of the Virginia 4/5 Term Loans due 2030, includes two one-year options that allow us to extend the initial maturity date, subject to the conditions specified in the agreements.

(2)Iron Mountain Data Centers Virginia 3, LLC, a wholly-owned subsidiary of IMI, has a credit agreement that includes a term loan facility (the "Virginia 3 Term Loans") and a letter of credit facility (collectively, the "Virginia 3 Credit Agreement"). The Virginia 3 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 3, LLC. As of December 31, 2025 and 2024, the Virginia 3 Term Loans have a weighted average interest rate of 6.2% and 6.7%, respectively.

(3)Iron Mountain Data Centers Virginia 7, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, has a credit agreement that includes a term loan facility (the "Virginia 7 Term Loans") and a letter of credit facility (collectively, the "Virginia 7 Credit Agreement"). The Virginia 7 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 7, LLC. As of December 31, 2025 and 2024, the interest rate in effect under the Virginia 7 Credit Agreement was 7.1% and 7.0%, respectively.

(4)Iron Mountain Data Centers Virginia 6, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 6/7 JV, LLC, has a credit agreement that includes a term loan facility (the "Virginia 6 Term Loans") and a letter of credit facility (collectively, the "Virginia 6 Credit Agreement"). The Virginia 6 Credit Agreement is secured by the equity interests and assets of Iron Mountain Data Centers Virginia 6, LLC. As of December 31, 2025 and 2024, the interest rate in effect under the Virginia 6 Credit Agreement was 7.1% and 7.1%, respectively.

(5)At December 31, 2024, Iron Mountain Data Centers Virginia 4/5 Subsidiary, LLC, a wholly-owned subsidiary of Iron Mountain Data Centers Virginia 4/5 JV, LP, had a credit agreement that included a term loan facility (the "Virginia 4/5 Term Loans due 2025") and a letter of credit facility (collectively, the "Virginia 4/5 Credit Agreement"). On November 3, 2025, Iron Mountain Data Centers Virginia 4/5 Subsidiary, LLC entered into a term loan agreement (the "Virginia 4/5 Term Loans due 2030"). Total net proceeds from the Virginia 4/5 Term Loans due 2030 were used to repay the Virginia 4/5 Term Loans due 2025. The Virginia 4/5 Term Loans due 2030 is secured by the property of Iron Mountain Data Centers Virginia 4/5 Subsidiary, LLC. The Virginia 4/5 Term Loans due 2025 bore interest at SOFR plus a credit spread adjustment of 0.1% plus 1.625% until its extinguishment in November 2025. The interest rate in effect under the Virginia 4/5 Term Loans due 2025 as of December 31, 2024 was 5.1%.

On September 10, 2025, IMI completed a private offering of:

SERIES OF NOTES	AGGREGATE PRINCIPAL AMOUNT
Euro Notes	€	1,200,000

Schedule of Redemption Dates and Prices of the Senior or Senior Subordinated Notes

The key terms of our indentures are as follows:

SENIOR NOTES	AGGREGATE PRINCIPAL AMOUNT		DIRECT OBLIGOR	MATURITY DATE	CONTRACTUAL INTEREST RATE	INTEREST PAYMENTS DUE	PAR CALL DATE(1)
47/8% Notes due 2027	$	1,000,000	IMI	September 15, 2027	47/8%	March 15 and September 15	September 15, 2025
51/4% Notes due 2028	$	825,000	IMI	March 15, 2028	51/4%	March 15 and September 15	March 15, 2025
5% Notes due 2028	$	500,000	IMI	July 15, 2028	5%	January 15 and July 15	July 15, 2025
7% Notes	$	1,000,000	IMI	February 15, 2029	7%	February 15 and August 15	August 15, 2025
47/8% Notes due 2029	$	1,000,000	IMI	September 15, 2029	47/8%	March 15 and September 15	September 15, 2027
51/4% Notes due 2030	$	1,300,000	IMI	July 15, 2030	51/4%	January 15 and July 15	July 15, 2028
41/2% Notes	$	1,100,000	IMI	February 15, 2031	41/2%	February 15 and August 15	February 15, 2029
5% Notes due 2032	$	750,000	IMIM Services	July 15, 2032	5%	May 15 and November 15	July 15, 2027
55/8% Notes	$	600,000	IMI	July 15, 2032	55/8%	January 15 and July 15	July 15, 2029
61/4% Notes	$	1,200,000	IMI	January 15, 2033	61/4%	January 15 and July 15	December 6, 2029
Euro Notes	€	1,200,000	IMI	January 15, 2034	43/4%	January 15 and July 15	September 10, 2030

(1)We may redeem the notes at any time, at our option, in whole or in part. Prior to the par call date, we may redeem the notes at the redemption price or make-whole premium specified in the applicable indenture, together with accrued and unpaid interest to, but excluding, the redemption date. On or after the par call date, we may redeem the notes at a price equal to 100% of the principal amount being redeemed, together with accrued and unpaid interest to, but excluding, the redemption date.

Schedule of Maturities of Long-term Debt

MATURITIES OF LONG-TERM DEBT (GROSS OF DISCOUNTS) ARE AS FOLLOWS:

YEAR	AMOUNT
2026	$	216,074
2027	2,330,763
2028	1,663,693
2029	2,137,476
2030	3,035,690
Thereafter	7,173,071
	16,556,767
Net Discounts	(12,294)
Net Deferred Financing Costs	(112,514)
Total Long-term Debt (including current portion)	$	16,431,959