Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

A. PRINCIPLES OF CONSOLIDATION

The accompanying financial statements reflect our financial position, results of operations, comprehensive income (loss), equity and cash flows on a consolidated basis. The accompanying financial statements include the results of those entities over which we have a controlling financial interest and we are deemed to be the primary beneficiary. All intercompany transactions and account balances have been eliminated.

B. USE OF ESTIMATES

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires us to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities at the date of the financial statements and for the period then ended. On an ongoing basis, we evaluate the estimates used. We base our estimates on historical experience, actuarial estimates, current conditions and various other assumptions that we believe to be reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities and are not readily apparent from other sources. Actual results may differ from these estimates.

C. CHANGES IN PRESENTATION

Certain items previously reported under specific financial statement captions have been reclassified to conform to the current year presentation.

D. FOREIGN CURRENCY

Local currencies are the functional currencies for our operations outside the United States, with the exception of certain foreign holding companies, whose functional currency is the United States dollar. In those instances where the local currency is the functional currency, assets and liabilities are translated at period-end exchange rates, and revenues and expenses are translated at average exchange rates for the applicable period. See Note 2.r.

E. CASH AND CASH EQUIVALENTS

Cash and cash equivalents include cash on hand and cash invested in highly liquid short-term securities, which have remaining maturities at the date of purchase of less than 90 days. Cash and cash equivalents are carried at cost, which approximates fair value.

F. ALLOWANCE FOR DOUBTFUL ACCOUNTS AND CREDIT MEMO RESERVES

We maintain an allowance for doubtful accounts and a credit memo reserve for estimated losses resulting from the potential inability of our customers to make required payments and potential disputes regarding billing and service issues. We evaluate and monitor the collectability of accounts receivable based on a combination of factors, including historical loss experience, assessments of trends in our aged receivables and credit memo activity, the location of our businesses, the composition of our customer base, our product and service lines, potential future macroeconomic factors, including natural disasters, and reasonable and supportable forecasts for expected future collectability of our outstanding receivables. Continued adjustments will be made, as it becomes evident, should there be any material change to reasonable and supportable forecasts that may impact our likelihood of collection. Our highly diverse global customer base, with no single customer accounting for more than approximately 1% of revenue during the years ended December 31, 2023, 2022 and 2021, limits our exposure to concentration of credit risk. Additionally, we write off uncollectible balances as circumstances warrant, generally no later than one year past due.

The rollforward of the allowance for doubtful accounts and credit memo reserves is as follows:

YEAR ENDED DECEMBER 31,	BALANCE AT BEGINNING OF THE YEAR		CREDIT MEMOS CHARGED TO REVENUE		ALLOWANCE FOR BAD DEBTS CHARGED TO EXPENSE		DEDUCTIONS AND OTHER(1)		BALANCE AT END OF THE YEAR
2023	$	54,143	$	92,881	$	32,692	$	(104,954)	$	74,762
2022	62,009		62,891		13,666		(84,423)		54,143
2021	56,981		47,931		26,896		(69,799)		62,009

(1)Primarily consists of the issuance of credit memos, the write-off of accounts receivable and the impact associated with currency translation adjustments.

G. CONCENTRATIONS OF CREDIT RISK

Financial instruments that potentially subject us to credit risk consist principally of cash and cash equivalents (including money market funds and time deposits) and accounts receivable. The only significant concentrations of liquid investments as of December 31, 2023 and 2022 related to investments in money market funds. As per our risk management investment policy, we limit exposure to concentration of credit risk by limiting the amount invested in any one mutual fund to a maximum of 1% of the fund's total assets or in any one financial institution to a maximum of $75,000. See

H. PREPAID EXPENSES AND ACCRUED EXPENSES

Prepaid expenses totaled $126,904 and $114,130 as of December 31, 2023 and 2022, respectively. There were no other items greater than 5% of total current assets included within Prepaid expenses and other as of December 31, 2023 and 2022.

Accrued expenses and other current liabilities with items greater than 5% of total current liabilities are shown separately and consist of the following:

	DECEMBER 31,
DESCRIPTION	2023		2022
Interest	$	175,218	$	128,272
Deferred purchase obligations, purchase price holdbacks and other	171,273		7,187
Dividends	202,392		194,272
Operating lease liabilities	291,795		288,738
Other	409,581		413,441
Accrued expenses and other current liabilities	$	1,250,259	$	1,031,910

I. PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment are stated at cost and depreciated using the straight-line method with the following useful lives (in years):

DESCRIPTION	RANGE
Buildings and building improvements	5 to 40
Leasehold improvements	5 to 10 or life of the lease (whichever is shorter)
Racking	1 to 20 or life of the lease (whichever is shorter)
Warehouse equipment/vehicles	1 to 10
Furniture and fixtures	1 to 10
Computer hardware and software	2 to 5

Property, plant and equipment (including financing leases in the respective categories), at cost, consist of the following:

	DECEMBER 31,
DESCRIPTION	2023		2022
Land	$	536,780	$	486,715
Buildings and building improvements	3,819,241		3,336,778
Leasehold improvements	1,166,810		1,079,419
Racking	2,054,046		2,058,054
Warehouse equipment/vehicles	526,965		493,128
Furniture and fixtures	46,094		49,610
Computer hardware and software	601,273		585,792
Construction in progress	1,622,780		936,269
Property, plant and equipment	$	10,373,989	$	9,025,765

Minor maintenance costs are expensed as incurred. Major improvements which extend the life, increase the capacity or improve the safety or the efficiency of property owned are capitalized and depreciated. Major improvements to leased buildings are capitalized as leasehold improvements and depreciated.

CAPITALIZED INTEREST

We capitalize interest expense during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is amortized over the useful lives of the assets. During the years ended December 31, 2023, 2022 and 2021, capitalized interest is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Capitalized interest	$	44,845	$	14,078	$	12,673

INTERNAL USE SOFTWARE

We develop various software applications for internal use. Computer software costs associated with internal use software are expensed as incurred until certain capitalization criteria are met. Third party consulting costs, as well as payroll and related costs for employees directly associated with, and devoting time to, the development of internal use computer software projects (to the extent time is spent directly on the project) are capitalized. Capitalization of costs, including costs incurred for upgrades and enhancements that provide additional functionality to our existing software, generally begins during the application development stage of the project, which occurs after it is probable that the project will be completed and used to perform the function intended. Capitalization ends when the asset is ready for its intended use. Capitalized internal use software costs are depreciated on a straight-line basis over the expected useful life of the software, commencing when the software is ready for its intended use. Computer software costs that are capitalized are periodically evaluated for impairment.

During the years ended December 31, 2023, 2022 and 2021, capitalized costs associated with the development of internal use computer software projects are as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Capitalized costs associated with the development of internal use computer software projects	$	64,488	$	44,152	$	48,557

ASSET RETIREMENT OBLIGATIONS

Entities are required to record the fair value of a liability for an asset retirement obligation in the period in which it is incurred. Asset retirement obligations represent the costs to replace or remove tangible long-lived assets required by law, regulatory rule or contractual agreement. Our asset retirement obligations are primarily the result of requirements under our facility lease agreements which generally have "return to original condition" clauses which would require us to remove or restore items such as shred pits, vaults, demising walls and office build-outs, among others. The significant assumptions used in estimating our aggregate asset retirement obligations are the timing of removals, the probability of a requirement to perform, estimated cost and associated expected inflation rates that are consistent with historical rates and credit-adjusted risk-free rates that approximate our incremental borrowing rate. Our asset retirement obligations at December 31, 2023 and 2022 were $36,602 and $36,119, respectively, and are included in Other Long-term Liabilities in our Consolidated Balance Sheets.

J. LEASES

We lease facilities for certain warehouses, data centers and office space. We also have land leases, including those on which certain facilities are located. The majority of our leased facilities are classified as operating leases that, on average, have initial lease terms of five to 10 years, with one or more lease renewal options to extend the lease term. Our lease renewal option terms generally range from one to five years. The exercise of the lease renewal option is at our sole discretion and may contain fixed rent, fair market value based rent or Consumer Price Index rent escalation clauses. We include option periods in the lease term when our failure to renew the lease would result in an economic disincentive, thereby making it reasonably certain that we will renew the lease. We recognize straight line rental expense over the life of the lease and any fair market value or Consumer Price Index rent escalations are recognized as variable lease expense in the period in which the obligation is incurred. In addition, we lease certain vehicles and equipment. Vehicle and equipment leases typically have lease terms ranging from one to seven years.

We account for all leases, both operating and financing, in accordance with Accounting Standards Codification ("ASC") Topic 842, Leases ("ASC 842"). Our accounting policy provides that leases with an initial term of 12 months or less will not be included within the lease right-of-use assets and lease liabilities recognized on our Consolidated Balance Sheets. We recognize the lease payments for those leases with an initial term of 12 months or less in our Consolidated Statements of Operations on a straight-line basis over the lease term.

The lease right-of-use assets and related lease liabilities are classified as either operating or financing. Lease right-of-use assets are calculated as the net present value of future payments plus any capitalized initial direct costs less any tenant improvements or lease incentives. Lease liabilities are calculated as the net present value of future payments. In calculating the present value of the lease payments, we utilize the rate stated in the lease (in the limited circumstances when such rate is explicitly stated) or, if no rate is explicitly stated, we utilize a rate that reflects our securitized incremental borrowing rate by geography for the lease term. We account for nonlease components (which include common area maintenance, taxes, and insurance) with the related lease component. Any variable nonlease components are not included within the lease right-of-use asset and lease liability on our Consolidated Balance Sheets, and instead, are reflected as an expense in the period incurred.

Operating and financing lease right-of-use assets and lease liabilities as of December 31, 2023 and 2022 are as follows:

	DECEMBER 31,
DESCRIPTION	2023		2022
Assets:
Operating lease right-of-use assets(1)	$	2,696,024	$	2,583,704
Financing lease right-of-use assets, net of accumulated depreciation(2)(3)	304,600		251,690
Liabilities:
Current
Operating lease liabilities	$	291,795	$	288,738
Financing lease liabilities(3)	39,089		43,857
Long-term
Operating lease liabilities	$	2,562,394	$	2,429,167
Financing lease liabilities(3)	310,776		289,048

(1)At December 31, 2023 and 2022, these assets are comprised of approximately 99% real estate related assets (which include land, buildings and racking) and 1% non-real estate related assets (which include warehouse equipment, vehicles, furniture and fixtures and computer hardware and software).

(2)At December 31, 2023, these assets are comprised of approximately 68% real estate related assets and 32% non-real estate related assets. At December 31, 2022, these assets are comprised of approximately 64% real estate related assets and 36% non-real estate related assets.

(3)Financing lease right-of-use assets, current financing lease liabilities and long-term financing lease liabilities are included within Property, Plant and Equipment, Net, Current portion of long-term debt and Long-term Debt, net of current portion, respectively, within our Consolidated Balance Sheets.

The components of the lease expense for the years ended December 31, 2023, 2022 and 2021 are as follows:

	YEAR ENDED DECEMBER 31,
DESCRIPTION	2023		2022		2021
Operating lease cost(1)	$	660,889	$	574,115	$	545,097
Financing lease cost:
Depreciation of financing lease right-of-use assets	$	42,089	$	42,708	$	50,970
Interest expense for financing lease liabilities	18,638		17,329		19,808

(1)Operating lease cost, the majority of which is included in Cost of sales, includes variable lease costs of $142,154, $119,184 and $111,949 for the years ended December 31, 2023, 2022 and 2021, respectively.

Weighted average remaining lease terms and discount rates as of December 31, 2023 and 2022 are as follows:

	DECEMBER 31, 2023				DECEMBER 31, 2022
	OPERATING LEASES		FINANCING LEASES		OPERATING LEASES		FINANCING LEASES
Remaining Lease Term	10.6 years		9.2 years		11.3 years		10.6 years
Discount Rate	6.6	%	6.1	%	6.4	%	5.8	%

The estimated minimum future lease payments (receipts) as of December 31, 2023 are as follows:

YEAR	OPERATING LEASES(1)		SUBLEASE INCOME		FINANCING LEASES(1)
2024	$	468,015	$	(6,969)	$	56,901
2025	456,638		(4,282)		127,074
2026	421,535		(2,979)		40,283
2027	389,307		(3,451)		30,098
2028	344,744		(48)		55,523
Thereafter	1,970,950		(48)		117,779
Total minimum lease payments (receipts)	4,051,189		$	(17,777)	427,658
Less amounts representing interest or imputed interest	1,197,000				77,793
Present value of lease obligations	$	2,854,189			$	349,865

(1)Estimated minimum future lease payments exclude variable common area maintenance charges, insurance and taxes.

At December 31, 2023, we had four leases which we have signed but which have not yet commenced and are not included in our lease obligation table above. The total undiscounted minimum lease payments for these leases are approximately $239,146 and have lease terms that range from 14 to 25 years. Each of these leases is expected to commence during 2024.

Other information: Supplemental cash flow information relating to our leases for the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
CASH PAID FOR AMOUNTS INCLUDED IN MEASUREMENT OF LEASE LIABILITIES:	2023		2022		2021
Operating cash flows used in operating leases	$	450,412	$	409,163	$	392,987
Operating cash flows used in financing leases (interest)	18,638		17,329		19,808
Financing cash flows used in financing leases	52,284		44,869		46,118
NON-CASH ITEMS:
Operating lease modifications and reassessments	$	86,948	$	179,094	$	144,310
New operating leases (including acquisitions and sale-leaseback transactions)	306,479		540,830		282,490

K. LONG-LIVED ASSETS

We review long-lived assets for impairment whenever events or changes in circumstances indicate the carrying amount of such assets may not be recoverable. Recoverability of these assets is determined by comparing the sum of the forecasted undiscounted net cash flows of the operation to which the assets relate to their carrying amount. The operations are generally distinguished by the business segment and geographic region in which they operate. If it is determined that we are unable to recover the carrying amount of the assets, the long-lived assets are written down, on a pro rata basis, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets. Long-lived assets, including finite-lived intangible assets, are amortized over their useful lives. Annually, or more frequently if events or circumstances warrant, we assess whether a change in the lives over which long-lived assets, including finite-lived intangible assets, are amortized is necessary.

Gain on disposal/write-down of property, plant and equipment, net for the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Gain on disposal/write-down of property, plant and equipment, net	$	12,825	$	93,268	$	172,041
The gains primarily consist of(1):	•Gains associated with sale and sale-leaseback transactions of approximately $19,500, of which approximately $18,500 relates to a sale-leaseback transaction of a facility in Singapore during the first quarter of 2023. These gains are partially offset by losses related to the disposal of assets associated with facility consolidations.		•Gains associated with sale and sale-leaseback transactions of approximately $94,500, of which (i) approximately $49,000 relates to sale and sale-leaseback transactions of 11 facilities and parcels of land in the United States during the second quarter of 2022, (ii) approximately $17,000 relates to sale-leaseback transactions of two facilities in the United States and one in Canada during the third quarter of 2022 and (iii) approximately $28,500 relates to sale and sale-leaseback transactions of 12 facilities and one parcel of land in the United States and one facility in the United Kingdom during the fourth quarter of 2022.		•Gains associated with sale and sale-leaseback transactions of approximately $164,000, of which (i) approximately $127,400 relates to sale-leaseback transactions of five facilities in the United Kingdom during the second quarter of 2021 and (ii) approximately $36,600 relates to sale and sale-leaseback transactions of nine facilities in the United States during the fourth quarter of 2021.

(1) The gains recognized during the years ended December 31, 2023, 2022 and 2021 are the result of our program to monetize a small portion of our industrial assets through sale and sale-leaseback transactions. The terms for these leases are consistent with the terms of our lease portfolio, which are disclosed in

L. GOODWILL AND OTHER INDEFINITE-LIVED INTANGIBLE ASSETS

Goodwill and intangible assets with indefinite lives are not amortized but are reviewed annually for impairment, or more frequently if impairment indicators arise. Other than goodwill, we currently have no intangible assets that have indefinite lives and which are not amortized.

We test goodwill annually on October 1, and more frequently if impairment indicators arise that would require an interim test. We have performed our annual goodwill impairment review as of October 1, 2023, 2022 and 2021. We concluded that as of October 1, 2023, 2022 and 2021, goodwill was not impaired.

REPORTING UNITS AS OF OCTOBER 1, 2022

Our reporting units at which level we performed our goodwill impairment analysis as of October 1, 2022 were as follows:

•North America Records and Information Management ("North America RIM") •Europe and South Africa Records and Information Management ("ESA RIM") •Middle East, North Africa and Turkey Information Management ("MENAT RIM") •Latin America Records and Information Management ("Latin America RIM")

•Asia Pacific Records and Information Management ("APAC RIM") •Entertainment Services •Global Data Center •Fine Arts •ALM

There were no changes to the composition of our reporting units between October 1, 2022 and December 31, 2022.

GOODWILL BY REPORTING UNIT AS OF DECEMBER 31, 2022

The carrying value of goodwill, net for each of our reporting units described above as of December 31, 2022 is as follows:

SEGMENT	REPORTING UNIT	CARRYING VALUE AS OF DECEMBER 31, 2022
Global RIM Business	North America RIM	$	2,667,400
	ESA RIM	521,949
	MENAT RIM	25,007
	Latin America RIM	109,069
	APAC RIM	497,792
	Entertainment Services	31,729
Global Data Center Business	Global Data Center	418,502
Corporate and Other	Fine Arts	33,908
	ALM	577,378
Total		$	4,882,734

2023 REPORTING UNIT CHANGES

During 2023, as a result of the realignment of our global managerial structure, we reassessed the composition of our reporting units. The realignment of our global managerial structure did not change the composition of our reportable segments (as described and defined in Note 11). The reassessment resulted in the following changes to our reporting units: (i) our South Africa business, which was previously managed with our other businesses in Europe as part of our former ESA RIM reporting unit, is now managed as part of our former MENAT RIM reporting unit and these will comprise our "MENATSA RIM" reporting unit and (ii) our other businesses in Europe are now managed as our "Europe RIM" reporting unit.

There were no changes to our other reporting units. We have reassigned goodwill associated with the reporting units impacted by the realignment on a relative fair value basis, where appropriate. The fair value of each of our new reporting units was determined based on the application of a combined weighted average approach of preliminary fair value multiples of revenue and earnings and discounted cash flow techniques. These fair values represent our best estimate and preliminary assessment of goodwill allocations to each of the new reporting units on a relative fair value basis. We have completed an interim goodwill impairment analysis before and after the reporting unit changes, and we have concluded that the goodwill associated with each of our reporting units was not impaired.

REPORTING UNITS AS OF OCTOBER 1, 2023

Our reporting units at which level we performed our goodwill impairment analysis as of October 1, 2023 were as follows:

•North America RIM •Europe RIM •MENATSA RIM •Latin America RIM •APAC RIM
•Entertainment Services •Global Data Center •Fine Arts •ALM

There were no changes to the composition of our reporting units between October 1, 2023 and December 31, 2023.

GOODWILL BY REPORTING UNIT AS OF DECEMBER 31, 2023

The carrying value of goodwill, net for each of our reporting units described above as of December 31, 2023 is as follows:

SEGMENT	REPORTING UNIT	CARRYING VALUE AS OF DECEMBER 31, 2023
Global RIM Business	North America RIM	$	2,694,093
	Europe RIM	541,860
	MENATSA RIM	26,502
	Latin America RIM	120,119
	APAC RIM	496,944
	Entertainment Services	32,427
Global Data Center Business	Global Data Center	478,930
Corporate and Other	Fine Arts	47,535
	ALM	579,502
Total		$	5,017,912

The fair value of our reporting units has generally been determined using a combined approach based on the present value of future cash flows (the "Discounted Cash Flow Model") and market multiples (the "Market Approach").

The Discounted Cash Flow Model incorporates significant assumptions including future revenue growth rates, operating margins, discount rates and capital expenditures. The Market Approach requires us to make assumptions related to Adjusted EBITDA (as defined in Note 11) multiples.

Changes in economic and operating conditions impacting these assumptions or changes in multiples could result in goodwill impairments in future periods. In conjunction with our annual goodwill impairment reviews, we reconcile the sum of the valuations of all of our reporting units to our market capitalization as of such dates.

The changes in the carrying value of goodwill attributable to each reportable segment for the years ended December 31, 2023 and 2022 are as follows:

	GLOBAL RIM BUSINESS		GLOBAL DATA CENTER BUSINESS		CORPORATE AND OTHER		TOTAL CONSOLIDATED
Goodwill balance, net of accumulated amortization, as of December 31, 2021	$	3,972,852	$	426,074	$	64,605	$	4,463,531
Tax deductible goodwill acquired during the year	—		—		912		912
Non-tax deductible goodwill acquired during the year	696		—		546,693		547,389
Fair value and other adjustments(1)	(12,199)		—		384		(11,815)
Currency effects	(108,403)		(7,572)		(1,308)		(117,283)
Goodwill balance, net of accumulated amortization, as of December 31, 2022	3,852,946		418,502		611,286		4,882,734
Tax deductible goodwill acquired during the year	—		—		11,928		11,928
Non-tax deductible goodwill acquired during the year	21,594		56,674		383		78,651
Fair value and other adjustments	(80)		—		2,333		2,253
Currency effects	37,485		3,754		1,107		42,346
Goodwill balance, net of accumulated amortization, as of December 31, 2023	$	3,911,945	$	478,930	$	627,037	$	5,017,912
Accumulated Goodwill Impairment Balance as of December 31, 2022	$	132,409	$	—	$	26,011	$	158,420
Accumulated Goodwill Impairment Balance as of December 31, 2023	$	132,409	$	—	$	26,011	$	158,420

(1) This amount primarily represents an adjustment to goodwill as a result of the deconsolidation of certain businesses, as described in Note 4.

M. FINITE-LIVED INTANGIBLE ASSETS AND LIABILITIES

I. CUSTOMER AND SUPPLIER RELATIONSHIP INTANGIBLE ASSETS

Customer and supplier relationship intangible assets, which are acquired through either business combinations or acquisitions of customer relationships, are generally amortized over periods ranging from 10 to 30 years. Customer and supplier relationship intangible assets are recorded based upon estimates of their fair value.

II. CUSTOMER INDUCEMENTS

Payments that are made to a customer in order to terminate the customer’s storage of records with its current records management vendor ("Permanent Withdrawal Fees"), or direct payments to a customer for which no distinct benefit is received in return, are collectively referred to as "Customer Inducements". Customer Inducements are treated as a reduction of the transaction price over the associated contract terms, which range from one to 10 years, and are included in storage and service revenue in the accompanying Consolidated Statements of Operations. If the customer terminates its relationship with us, the unamortized carrying value of the Customer Inducement intangible asset is charged to revenue. However, in the event of such termination, we generally collect, and record as revenue, Permanent Withdrawal Fees that generally equal or exceed the amount of the unamortized Customer Inducement intangible asset.

III. DATA CENTER INTANGIBLE ASSETS AND LIABILITIES

Finite-lived intangible assets associated with our Global Data Center Business consist of the following:

DATA CENTER IN-PLACE LEASE INTANGIBLE ASSETS AND DATA CENTER TENANT RELATIONSHIP INTANGIBLE ASSETS

Data center in-place lease intangible assets ("Data Center In-Place Leases") and data center tenant relationship intangible assets ("Data Center Tenant Relationships") reflect the value associated with acquiring a data center operation with active tenants as of the date of acquisition. The value of Data Center In-Place Leases is determined based upon an estimate of the economic costs (such as lost revenues, tenant improvement costs, commissions, legal expenses and other costs to acquire new data center leases) avoided by acquiring a data center operation with active tenants. Data Center In-Place Leases are amortized over the weighted average remaining term of the acquired data center leases. The value of Data Center Tenant Relationships is determined based upon an estimate of the economic costs avoided upon lease renewal of the acquired tenants, based upon expectations of lease renewal. Data Center Tenant Relationships are amortized over the weighted average remaining anticipated life of the relationship with the acquired tenant.

DATA CENTER ABOVE-MARKET AND BELOW-MARKET IN-PLACE LEASE INTANGIBLE ASSETS

Data center above-market in-place lease intangible assets ("Data Center Above-Market Leases") and data center below-market in-place lease intangible assets ("Data Center Below-Market Leases") are recorded at the net present value of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of the fair market lease rates for each corresponding in-place lease. Data Center Above-Market Leases and Data Center Below-Market Leases are amortized over the remaining non-cancellable term of the acquired in-place lease to storage revenue.

The gross carrying amount and accumulated amortization of our finite-lived intangible assets as of December 31, 2023 and 2022, respectively, are as follows:

	DECEMBER 31, 2023						DECEMBER 31, 2022
DESCRIPTION	GROSS CARRYING AMOUNT		ACCUMULATED AMORTIZATION		NET CARRYING AMOUNT		GROSS CARRYING AMOUNT		ACCUMULATED AMORTIZATION		NET CARRYING AMOUNT
Assets:
Customer and supplier relationship intangible assets(1)	$	2,144,641	$	(933,084)	$	1,211,557	$	2,162,154	$	(823,392)	$	1,338,762
Customer inducements(1)	47,565		(25,562)		22,003		47,794		(26,158)		21,636
Data center lease-based intangible assets(1)(2)	141,628		(95,422)		46,206		272,649		(209,902)		62,747
Third-party commissions asset and other(3)	77,638		(39,323)		38,315		83,297		(28,581)		54,716
Liabilities:
Data center below-market leases(4)	$	10,873	$	(5,772)	$	5,101	$	12,831	$	(7,806)	$	5,025

(1)Included in Customer and supplier relationship and other intangible assets in the accompanying Consolidated Balance Sheets.

(2)Data center lease-based intangible assets includes Data Center In-Place Leases, Data Center Tenant Relationships and Data Center Above-Market Leases.

(3)Included in Other (within Other Assets, Net) in the accompanying Consolidated Balance Sheets.

(4)Included in Other long-term liabilities in the accompanying Consolidated Balance Sheets.

Amortization expense associated with finite-lived intangible assets, revenue reduction associated with the amortization of Customer Inducements and net revenue reduction associated with the amortization of Data Center Above-Market Leases and Data Center Below-Market Leases for the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Amortization expense included in depreciation and amortization associated with:
Customer and supplier relationship intangible assets	$	153,128	$	156,779	$	117,761
Data center in-place leases and tenant relationships	22,322		16,955		42,333
Third-party commissions asset and other	12,541		16,148		6,987
Revenue reduction associated with amortization of:
Customer inducements and data center above-market and below-market leases	$	7,036	$	8,119	$	8,852

Estimated amortization expense for existing finite-lived intangible assets (excluding Contract Costs, as defined and disclosed in Note 2.s.) is as follows:

	ESTIMATED AMORTIZATION
YEAR	INCLUDED IN DEPRECIATION AND AMORTIZATION		REVENUE REDUCTION ASSOCIATED WITH CUSTOMER INDUCEMENTS AND DATA CENTER ABOVE-MARKET AND BELOW-MARKET LEASES
2024	$	187,933	$	5,982
2025	173,432		3,494
2026	156,946		2,607
2027	127,284		2,096
2028	116,387		1,729
Thereafter	533,747		1,343

N. DEFERRED FINANCING COSTS

Deferred financing costs are amortized over the life of the related debt. If debt is retired early, the related unamortized deferred financing costs are written off in the period the debt is retired and included as a component of Other expense (income), net. See Note 7.

O. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES

Derivative instruments are measured at fair value and are recorded as either assets or liabilities in our Consolidated Balance Sheets. Periodically, we acquire derivative instruments that are intended to hedge either cash flows or values that are subject to foreign exchange or other market price risk and not for trading purposes. We have formally documented our hedging relationships, including identification of the hedging instruments and the hedged items, as well as our risk management objectives and strategies for undertaking each hedge transaction. Given the recurring nature of our revenues and the long-term nature of our asset base, we have the ability and the preference to use long-term, fixed interest rate debt to finance our business, thereby preserving our long-term returns on invested capital. We may use interest rate swaps as a tool to maintain our targeted level of fixed rate debt. In addition, we may enter into cross-currency swaps to hedge the variability of exchange rates between the United States dollar and the currencies of our foreign subsidiaries, as well as interest rates. We may also use borrowings in foreign currencies, either obtained in the United States or by our foreign subsidiaries, to hedge foreign currency risk associated with our international investments. Gains and losses realized as a result of the maturing or termination of our interest rate swaps and cross-currency swaps are reflected as operating cash flows within our Consolidated Statements of Cash Flows. As of December 31, 2023 and 2022, none of our derivative instruments contained credit-risk related contingent features. See Note 6.

P. FAIR VALUE MEASUREMENTS

Entities are permitted under GAAP to elect to measure certain financial instruments and certain other items at either fair value or cost. We have elected the cost measurement option in all circumstances where we had an option.

Our financial assets or liabilities that are carried at fair value are required to be measured using inputs from the three levels of the fair value hierarchy. A financial asset or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows:

Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date.

Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

Level 3—Unobservable inputs that reflect our assumptions about the assumptions that market participants would use in pricing the asset or liability.

The assets and liabilities carried at fair value and measured on a recurring basis as of December 31, 2023 and 2022, respectively, are as follows:

			FAIR VALUE MEASUREMENTS AT DECEMBER 31, 2023 USING
DESCRIPTION	TOTAL CARRYING VALUE AT DECEMBER 31, 2023		QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)			SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)			SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Money Market Funds(1)	$	66,008	$	—		$	66,008		$	—
Time Deposits(1)	15,913		—			15,913			—
Trading Securities	9,952		6,149		(2)	3,803		(3)	—
Derivative Assets(4)	6,359		—			6,359			—
Derivative Liabilities(4)	5,769		—			5,769			—
Deferred Purchase Obligations(5)	208,265		—			—			208,265

			FAIR VALUE MEASUREMENTS AT DECEMBER 31, 2022 USING
DESCRIPTION	TOTAL CARRYING VALUE AT DECEMBER 31, 2022		QUOTED PRICES IN ACTIVE MARKETS (LEVEL 1)			SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)			SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Money Market Funds(1)	$	11,311	$	—		$	11,311		$	—
Time Deposits(1)	1,102		—			1,102			—
Trading Securities	9,462		9,426		(2)	36		(3)	—
Derivative Assets(4)	51,396		—			51,396			—
Derivative Liabilities(4)	489		—			489			—
Deferred Purchase Obligations(5)	193,033		—			—			193,033

(1)Money market funds and time deposits are measured based on quoted prices for similar assets and/or subsequent transactions.

(2)Certain trading securities are measured at fair value using quoted market prices.

(3)Certain trading securities are measured based on inputs other than quoted market prices that are observable.

(4)Derivative assets and liabilities include (i) interest rate swap agreements, and (ii) cross-currency swap agreements to hedge the variability of exchange rate impacts between the United States dollar and the Euro and certain of our Euro denominated subsidiaries. Our derivative financial instruments are measured using industry standard valuation models using market-based observable inputs, including interest rate curves, forward and spot prices for currencies and implied volatilities. Credit risk is also factored into the determination of the fair value of our derivative financial instruments. See Note 6 for additional information on our derivative financial instruments.

(5)Primarily relates to the fair value of the Deferred Purchase Obligation associated with the ITRenew Transaction (each as defined in Note 3), which was determined utilizing a Monte Carlo model and takes into account our forecasted projections as it relates to the underlying performance of the business. The Monte Carlo simulation model incorporates assumptions as to expected gross profits over the applicable achievement period, including adjustments for the volatility of timing and amount of the associated revenue and costs, as well as discount rates that account for the risk of the underlying arrangement and overall market risks. Any material change to these assumptions may result in a significantly higher or lower fair value of the Deferred Purchase Obligation. During the fourth quarter of 2022, we recorded a change in the estimated fair value of the Deferred Purchase Obligation as described in Note 2.v. The change in value of the Deferred Purchase Obligation during the year ended December 31, 2023 was driven by the accretion of the obligation to present value.

There were no material items that were measured at fair value on a non-recurring basis for the years ended December 31, 2023 and 2022 other than (i) the reporting units as presented in our goodwill impairment analysis (as disclosed in Note 2.l.); (ii) assets acquired and liabilities assumed through our acquisitions (as disclosed in Note 3); (iii) the redemption value of recently acquired noncontrolling interests and previously held equity interests (both as disclosed in Note 3); (iv) contributions to our equity method investments; and (v) the fair value of our retained investment of our deconsolidated businesses (as described in Note 4), all of which are based on Level 3 inputs.

The fair value of our long-term debt, which was determined based on Level 2 and Level 3 inputs, is disclosed in Note 7. Long-term debt is measured at cost in our Consolidated Balance Sheets as of December 31, 2023 and 2022.

Q. REDEEMABLE NONCONTROLLING INTERESTS

Certain unaffiliated third parties own noncontrolling interests in certain of our consolidated subsidiaries. The underlying agreements between us and our noncontrolling interest shareholders for these subsidiaries contain provisions under which the noncontrolling interest shareholders can require us to purchase their respective interests in such subsidiaries at certain times and at a purchase price as stipulated in the underlying agreements (generally at fair value). These put options make these noncontrolling interests redeemable and, therefore, these noncontrolling interests are classified as temporary equity outside of stockholders’ equity. Redeemable noncontrolling interests are reported at the higher of their redemption value or the noncontrolling interest holders’ proportionate share of the underlying subsidiaries net carrying value. Increases or decreases in the redemption value of the noncontrolling interest are offset against Additional Paid-in Capital.

When our noncontrolling interests become mandatorily redeemable, they are included as a component of either Accrued expenses and other current liabilities or Other long-term liabilities on our Consolidated Balance Sheets, depending on the timing of the redemption.

R. ACCUMULATED OTHER COMPREHENSIVE ITEMS, NET

The changes in Accumulated other comprehensive items, net for the years ended December 31, 2023, 2022 and 2021 are as follows:

	FOREIGN CURRENCY  TRANSLATION AND OTHER ADJUSTMENTS		CHANGE IN FAIR VALUE OF DERIVATIVE INSTRUMENTS		TOTAL
Balance as of December 31, 2020	$	(206,190)	$	(49,703)	$	(255,893)
Other comprehensive (loss) income:
Foreign currency translation and other adjustments	(134,834)		—		(134,834)
Change in fair value of derivative instruments	—		52,380		52,380
Total other comprehensive (loss) income	(134,834)		52,380		(82,454)
Balance as of December 31, 2021	(341,024)		2,677		(338,347)
Other comprehensive (loss) income:
Foreign currency translation and other adjustments	(113,485)		—		(113,485)
Change in fair value of derivative instruments	—		9,829		9,829
Total other comprehensive (loss) income	(113,485)		9,829		(103,656)
Balance as of December 31, 2022	(454,509)		12,506		(442,003)
Other comprehensive income (loss):
Foreign currency translation and other adjustments	80,881		—		80,881
Change in fair value of derivative instruments	—		(2,454)		(2,454)
Reclassifications from Accumulated Other Comprehensive Items, net	—		(7,580)		(7,580)
Total other comprehensive income (loss)	80,881		(10,034)		70,847
Balance as of December 31, 2023	$	(373,628)	$	2,472	$	(371,156)

S. REVENUES

Our revenues consist of storage rental revenues as well as service revenues and are reflected net of sales and value-added taxes. Storage rental revenues, which are considered a key driver of financial performance for the storage and information management services industry, consist primarily of recurring periodic rental charges related to the storage of materials or data (generally on a per unit basis) that are typically retained by customers for many years and of revenues associated with our data center operations. Service revenues include charges for related service activities, the most significant of which include: (1) the handling of records, including the addition of new records, temporary removal of records from storage, refiling of removed records, customer termination and permanent withdrawal fees, project revenues and courier operations consisting primarily of the pickup and delivery of records upon customer request; (2) destruction services, consisting primarily of (i) secure shredding of sensitive documents and the subsequent sale of shredded paper for recycling, the price of which can fluctuate from period to period, and (ii) the decommissioning, data erasure, processing and disposition or sale of IT hardware and component assets; (3) digital solutions, including the scanning, imaging and document conversion services of active and inactive records, and consulting services; and (4) data center services, including set up, monitoring and support of our customers' assets which are protected in our data center facilities, and special project services, including data center fitout.

We account for our revenue in accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"), with the exception of our data center revenue, as described below. Customers are generally billed monthly based on contractually agreed-upon terms, and storage rental and service revenues are recognized in the month the respective storage rental or service is provided, in line with the transfer of control to the customer. When storage rental fees or services are billed in advance, amounts related to future storage rental or prepaid service contracts are accounted for as deferred revenue and recognized upon the transfer of control to the customer, generally ratably over the contract term. Customer contracts generally include promises to provide monthly recurring storage and related services that are essentially the same over time and have the same pattern of transfer of control to the customer; therefore, most performance obligations represent a promise to deliver a series of distinct services over time (as determined for purposes of ASC 606, a "series"). For those contracts that qualify as a series, we apply the "right to invoice" practical expedient as we have a right to consideration from the customer in an amount that corresponds directly with the value of the underlying performance obligation transferred to the customer to date. Additionally, each purchasing decision is fully in the control of the customer; therefore, consideration beyond the current reporting period is variable and allocated to the specific period to which the consideration relates, which is consistent with the practical expedient. Revenue from product sales, the significant majority of which are shred paper and IT asset sales, is recognized at the point in time at which control transfers to the customer, which is generally upon shipment.

Our Global Data Center Business features storage rental provided to the customer at contractually specified rates over a fixed contractual period. The revenue related to the storage component of our Global Data Center Business is recognized on a straight-line basis over the contract term in accordance with ASC 842. The revenue related to the service component of our Global Data Center Business is recognized in the period the related services are provided.

From time to time, we make payments to entities that are also customers under a revenue contract. These payments are primarily comprised of (i) Customer Inducements and (ii) payments to customers of our ALM business under revenue sharing arrangements for the remarketing of the customer's disposed IT assets. Customer Inducements do not represent payments for a distinct service, and, as such, are treated as a reduction of the transaction price over periods ranging from one to 10 years. Payments for disposed IT assets are for a distinct good and, as such, are expensed as cost of sales in the period the revenue share is known or estimable.

The costs associated with the initial movement of customer records into physical storage and certain commissions are considered costs to fulfill or obtain customer contracts (collectively, "Contract Costs"). The following describes our significant Contract Costs:

INTAKE COSTS (AND ASSOCIATED DEFERRED REVENUE)

The costs of the initial intake of customer records into physical storage ("Intake Costs") are deferred and amortized as a component of depreciation and amortization in our Consolidated Statements of Operations generally over three years, consistent with the transfer of the performance obligation to the customer to which the asset relates. In instances where such Intake Costs are billed to the customer, the associated revenue is deferred and recognized over the same three-year period.

COMMISSIONS

Certain commission payments that are directly associated with the fulfillment of long-term contracts are capitalized and amortized as a component of depreciation and amortization in our Consolidated Statements of Operations generally over three years, consistent with the transfer of the performance obligation to the customer to which the asset relates. We also apply the practical expedient to expense certain commission payments as incurred when the amortization period for those commission payments is one year or less.

Contract Costs, which are included as a component of Other within Other Assets, Net as of December 31, 2023 and 2022 are as follows:

	DECEMBER 31, 2023						DECEMBER 31, 2022
DESCRIPTION	GROSS CARRYING AMOUNT		ACCUMULATED AMORTIZATION		NET CARRYING AMOUNT		GROSS CARRYING AMOUNT		ACCUMULATED AMORTIZATION		NET CARRYING AMOUNT
Intake Costs asset	$	76,150	$	(39,617)	$	36,533	$	68,345	$	(42,132)	$	26,213
Commissions asset	156,639		(64,279)		92,360		133,145		(58,949)		74,196

Amortization expense associated with the Intake Costs and Commissions assets for the years ended December 31, 2023, 2022 and 2021 are as follows:

	YEAR ENDED DECEMBER 31,
DESCRIPTION	2023		2022		2021
Intake Costs asset	$	18,904	$	18,117	$	17,530
Commissions asset	43,413		40,612		30,739

Estimated amortization expense for Contract Costs is as follows:

YEAR	ESTIMATED AMORTIZATION
2024	$	61,379
2025	44,161
2026	23,353

Deferred revenue liabilities are reflected as follows in our Consolidated Balance Sheets:

		DECEMBER 31,
DESCRIPTION	LOCATION IN BALANCE SHEET	2023		2022
Deferred revenue - Current	Deferred revenue	$	325,665	$	328,910
Deferred revenue - Long-term	Other Long-term Liabilities	100,770		32,960

DATA CENTER LESSOR CONSIDERATIONS

Our Global Data Center Business features storage rental provided to customers at contractually specified rates over a fixed contractual period. Our data center revenue contracts are accounted for in accordance with ASC 842. ASC 842 provides a practical expedient which allows lessors to account for nonlease components with the related lease component if both the timing and pattern of transfer are the same for nonlease components and the lease component, and the lease component, if accounted for separately, would be classified as an operating lease. The single combined component is accounted for under ASC 842 if the lease component is the predominant component and is accounted for under ASC 606 if the nonlease components are the predominant components. We have elected to take this practical expedient. Our data center revenue contracts may contain Consumer Price Index rent escalation clauses. Consumer Price Index rent escalation clauses are considered variable lease payments and are recognized as income in the period earned.

Storage rental revenue associated with our Global Data Center Business for the years ended December 31, 2023, 2022 and 2021 are as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Storage rental revenue	$	474,066	$	372,208	$	289,592

The revenue related to the service component of our Global Data Center Business is recognized in the period the related services are provided.

The future minimum lease payments we expect to receive under non-cancellable data center operating leases for which we are the lessor, excluding month to month leases, for the next five years are as follows:

YEAR	FUTURE MINIMUM LEASE PAYMENTS
2024	$	393,046
2025	388,491
2026	375,800
2027	342,441
2028	296,270

T. STOCK-BASED COMPENSATION

We record stock-based compensation expense, utilizing the straight-line method, for the cost of stock options, restricted stock units ("RSUs"), and performance units ("PUs") (together, "Employee Stock-Based Awards").

RETIREMENT ELIGIBLE CRITERIA

For our Employee Stock-Based Awards made on or after March 1, 2022, we have included the following retirement provision:

•Upon an employee’s retirement on or after attaining age 55 with at least five years of service, if the sum of (i) the award recipient’s age at retirement and (ii) the award recipient’s years of service with us totals at least 65, the award recipient is entitled to continued vesting of any outstanding Employee Stock-Based Awards, provided that their retirement occurs on or after a minimum of six months from the grant date (the "Retirement Criteria").

•Accordingly, (i) grants of Employee Stock-Based Awards to an employee who has met the Retirement Criteria on or before the date of grant, or will meet the Retirement Criteria before the six month anniversary in the year of the grant, will be expensed over six months from the date of grant and (ii) grants of Employee Stock-Based Awards to employees who will meet the Retirement Criteria during the award’s normal vesting period will be expensed between the date of grant and the date upon which the award recipient meets the Retirement Criteria.

•Stock options and RSUs granted to award recipients who meet the Retirement Criteria will be delivered to the award recipient based upon the original vesting schedule. If an award recipient retires and has met the Retirement Criteria, stock options will remain exercisable until the original expiration date of the stock options. PUs granted to award recipients who meet the Retirement Criteria will be delivered in accordance with the original vesting schedule of the applicable PU award and remain subject to the same performance conditions.

Stock-based compensation expense for Employee Stock-Based Awards included in the accompanying Consolidated Statements of Operations for the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Stock-based compensation expense	$	73,799	$	56,861	$	61,001
Stock-based compensation expense, after tax	68,309		52,600		59,243

The substantial majority of stock-based compensation expense for Employee Stock-Based Awards is included in Selling, general and administrative expenses in the accompanying Consolidated Statements of Operations.

STOCK OPTIONS

Options are generally granted with exercise prices equal to the market price of the stock on the date of grant; however, in certain instances, options are granted at exercise prices greater than the market price of the stock on the date of grant. We issue options that become exercisable ratably over a period three years from the date of grant and have a contractual life of 10 years from the date of grant, unless the holder’s employment is terminated sooner. Our non-employee directors are considered employees for purposes of our stock option plans and stock option reporting.

Our equity compensation plans generally provide that, upon a vesting change in control (as defined in each plan), any unvested options and other awards granted thereunder shall vest immediately if an employee is terminated as a result of the change in control or terminates their own employment for good reason (as defined in each plan). On January 20, 2015, our stockholders approved the adoption of the Iron Mountain Incorporated 2014 Stock and Cash Incentive Plan, as amended (the "2014 Plan").

In May 2021, our stockholders approved an amendment to the 2014 Plan to (i) increase the number of shares of our common stock authorized for issuance thereunder by 8,000,000 from 12,750,000 to 20,750,000, (ii) extend the termination date of the 2014 Plan from May 24, 2027 to May 12, 2031, (iii) provide that, other than in specified circumstances, no equity-based award will vest before the first anniversary of the date of grant and (iv) provide that dividends and dividend equivalents are not paid with respect to stock options or stock appreciation rights.

A total of 20,750,000 shares of common stock have been reserved for grants of options and other rights under our various stock incentive plans, including the 2014 Plan. The number of shares available for grant under our various stock incentive plans at December 31, 2023 was 6,204,098.

The fair value of stock options granted in 2023, 2022 and 2021 was $10.98, $7.44 and $3.23 per share, respectively. These values were estimated on the date of grant using the Black-Scholes option pricing model. The assumptions used for stock option grants in the years ended December 31, 2023, 2022 and 2021 are as follows:

	YEAR ENDED DECEMBER 31,
STOCK OPTION GRANT ASSUMPTIONS	2023		2022		2021
Expected volatility(1)	29.1	%	28.0	%	28.3	%
Risk-free interest rate(2)	3.92	%	1.72	%	1.45	%
Expected dividend yield(3)	5	%	5	%	7	%
Expected life(4)	10.0 years		10.0 years		10.0 years

(1)Expected volatility is calculated utilizing daily historical volatility over a period that equates to the expected life of the option.

(2)Risk-free interest rate is based on the United States Treasury interest rates whose term is consistent with the expected life (estimated period of time outstanding) of the stock options.

(3)Expected dividend yield is considered in the option pricing model and represents our annualized expected per share dividends over the trade price of our common stock at the date of grant.

(4)Expected life of the stock options granted is estimated using the historical exercise behavior of employees.

A summary of stock option activity for the year ended December 31, 2023 is as follows:

	OPTIONS	WEIGHTED AVERAGE EXERCISE PRICE		WEIGHTED AVERAGE REMAINING CONTRACTUAL TERM (YEARS)	AGGREGATE INTRINSIC VALUE
Outstanding at December 31, 2022	4,226,319	$	36.89
Granted	157,132	52.58
Exercised	(322,854)	32.66
Outstanding at December 31, 2023	4,060,597	$	37.84	4.44	$	130,548
Options exercisable at December 31, 2023	3,619,289	$	36.85	3.98	$	119,903
Options expected to vest	441,308	$	45.86	8.20	$	10,645

RESTRICTED STOCK UNITS

Our RSUs generally have a vesting period of three years from the date of grant. However, RSUs granted to our non-employee directors vest immediately upon grant. All RSUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of RSUs in cash upon the vesting date of the associated RSU and will be forfeited if the RSU does not vest. The fair value of RSUs is the excess of the market price of our common stock at the date of grant over the holder's purchase price (which is typically zero).

The fair value of RSUs vested during the years ended December 31, 2023, 2022 and 2021 are as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Fair value of RSUs vested	$	32,664	$	27,078	$	29,332

A summary of RSU activity for the year ended December 31, 2023 is as follows:

	RSUs	WEIGHTED-AVERAGE GRANT-DATE FAIR VALUE
Non-vested at December 31, 2022	1,306,115	$	43.43
Granted	1,035,583	53.02
Vested	(762,683)	42.83
Forfeited	(218,751)	48.63
Non-vested at December 31, 2023	1,360,264	$	50.24

PERFORMANCE UNITS

The PUs we issue vest based on our performance against predefined operational performance and relative total shareholder return based targets over a three-year performance period. The vesting is subject to a minimum level of return on invested capital in the third year of the performance period, and the number of PUs earned is based on certain metrics determined at the outset of the performance period.

For grants issued in 2023 and 2022, the number of PUs earned is based on:

•either (i) the revenue performance for each year averaged at the end of the three-year performance period, or (ii) if (a) absolute total shareholder return is positive at the end of the three-year performance period and (b) a predetermined revenue hurdle is achieved in the third year of the performance period, then the revenue performance achieved in the third year of the performance period; and

•the total return on our common stock relative to the Morgan Stanley Capital International (“MSCI”) United States REIT Index.

For grants issued in 2021, the number of PUs earned is based on:

•the revenue performance for each year averaged at the end of the three-year performance period;

•the revenue exit rate of new products in the last quarter of the three-year performance period; and

•the total return on our common stock relative to the MSCI United States REIT Index.

The number of PUs earned for grants made in 2023 and 2022 will range from 0% to approximately 350% of the initial award, and the number of PUs earned for grants made in 2021 will range from 0% to 200%.

All of our PUs will be settled in shares of our common stock and are subject to cliff vesting three years from the date of the original PU grant. As detailed above, PUs granted are subject to the Retirement Criteria. PUs are generally expensed over the three-year performance period, unless they are granted to a recipient who meets the Retirement Criteria, for which expense will be recognized as described above. PUs granted to recipients who meet the Retirement Criteria will continue to vest and be delivered in accordance with the original vesting schedule of the applicable PU award and remain subject to the same performance conditions.

All PUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of PUs in cash upon the settlement date of the associated PU and will be forfeited if the PU does not vest.

During the years ended December 31, 2023, 2022 and 2021, we issued 641,412, 435,675 and 488,953 PUs, respectively. We forecast the likelihood of achieving the predefined targets for our PUs in order to calculate the expected PUs to be earned. We record a compensation charge based on either the forecasted PUs to be earned (during the performance period) or the actual PUs earned (at the three-year anniversary of the grant date) over the vesting period for each of the awards. The fair value of PUs based on our performance against predefined targets is the excess of the market price of our common stock at the date of grant over the purchase price (which is typically zero). For PUs earned based on a market condition, we utilize a Monte Carlo simulation to fair value these awards at the date of grant.

The fair value of earned PUs that vested during the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Fair value of earned PUs that vested	$	34,896	$	20,059	$	29,701

A summary of PU activity for the year ended December 31, 2023 is as follows:

	ORIGINAL PU AWARDS	PU ADJUSTMENT(1)	TOTAL PU AWARDS	WEIGHTED-AVERAGE GRANT-DATE FAIR VALUE
Non-vested at December 31, 2022	830,173	(484,550)	345,623	$	45.65
Granted	641,412	—	641,412	55.76
Prior year grant adjustments for performance(1)	—	160,993	160,993	42.66
Vested	(615,588)	—	(615,588)	56.69
Forfeited	(51,087)	—	(51,087)	53.60
Non-vested at December 31, 2023	804,910	(323,557)	481,353	$	43.16

(1)Represents an increase or decrease in the number of original PUs awarded based on either the final performance criteria or market condition achievement at the end of the performance period of such PUs.

EMPLOYEE STOCK PURCHASE PLAN

We offer an Employee Stock Purchase Plan ("ESPP") in which participation is available to substantially all United States and Canadian employees who meet certain service eligibility requirements. Shares of our common stock may be purchased by eligible employees at six-month intervals at 95% of the fair market price at the end of each six-month period, without a look-back feature, up to a maximum of 15% of their gross compensation during the offering period. We do not recognize compensation expense for the ESPP shares purchased. The number of shares of Common Stock authorized for issuance under our ESPP is 2,000,000. For the years ended December 31, 2023, 2022 and 2021, there were 120,647, 112,486 and 112,297 shares, respectively, purchased under the ESPP. As of December 31, 2023, we have 870,857 shares available under the ESPP.

As of December 31, 2023, unrecognized compensation cost related to the unvested portion of our Employee Stock-Based Awards, inclusive of our estimated achievement of the performance metrics, was $61,799 and is expected to be recognized over a weighted-average period of 1.9 years.

We issue shares of our common stock for the exercises of stock options, and the vesting of RSUs, PUs and shares of our common stock under our ESPP from unissued reserved shares.

U. ACQUISITION AND INTEGRATION COSTS

Acquisition and integration costs represent operating expenditures directly associated with the closing and integration activities of our business acquisitions that have closed, or are highly probable of closing, and include (i) advisory, legal and professional fees to complete business acquisitions and (ii) costs to integrate acquired businesses into our existing operations, including move, severance and system integration costs (collectively, "Acquisition and Integration Costs"). Acquisition and integration costs for the years ended December 31, 2023, 2022 and 2021 were $25,875, $47,746 and $12,764, respectively.

V. OTHER EXPENSE (INCOME), NET

Other expense (income), net for the years ended December 31, 2023, 2022 and 2021 consists of the following:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Foreign currency transaction losses (gains), net(1)	$	36,799	$	(61,684)	$	(15,753)
Debt extinguishment expense	—		671		—
Other, net(2)(3)(4)	71,841		(8,768)		(177,051)
Other expense (income), net	$	108,640	$	(69,781)	$	(192,804)

(1)The gain or loss on foreign currency transactions, calculated as the difference between the historical exchange rate and the exchange rate at the applicable measurement date, includes gains or losses primarily related to (i) certain foreign currency denominated intercompany obligations of our foreign subsidiaries to us and between our foreign subsidiaries, which are not considered permanently invested, and (ii) borrowings in certain foreign currencies under the Revolving Credit Facility (as defined in Note 7).

(2)Other, net for the year ended December 31, 2023 consists primarily of a loss of approximately $38,000 associated with the remeasurement to fair value of our previously held equity interest in the Clutter JV (as defined and discussed in Note 5), as well as losses on our equity method investments and the change in value of the Deferred Purchase Obligation.

(3)Other, net for the year ended December 31, 2022 consists primarily of (i) a gain of approximately $93,600 associated with the remeasurement of the Deferred Purchase Obligation to the present value of our best estimate of fair value and (ii) a gain of approximately $35,800 associated with the Clutter Transaction (as defined in Note 5), partially offset by (iii) a loss of approximately $105,800 associated with the OSG Deconsolidation (as defined in Note 4) and (iv) losses on our equity method investments.

(4)Other, net for the year ended December 31, 2021 consists primarily of (i) a gain of approximately $179,000 associated with our IPM Divestment (as defined in Note 4) and (ii) a gain of approximately $20,300 associated with the loss of control and related deconsolidation, as of May 18, 2021, of one of our wholly-owned Netherlands subsidiaries, for which we had value-added tax liability exposure that was recorded in 2019, partially offset by (iii) losses on our equity method investments.

W. INCOME TAXES

Accounting for income taxes requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the tax and financial reporting bases of assets and liabilities and for loss and credit carryforwards. Valuation allowances are provided when recovery of deferred tax assets does not meet the more likely than not standard as defined in GAAP. We have elected to recognize interest and penalties associated with uncertain tax positions as a component of the Provision (benefit) for income taxes in the accompanying Consolidated Statements of Operations.

X. INCOME (LOSS) PER SHARE—BASIC AND DILUTED

Basic income (loss) per common share is calculated by dividing income (loss) by the weighted average number of common shares outstanding. The calculation of diluted income (loss) per share is consistent with that of basic income (loss) per share but gives effect to all potential common shares (that is, securities such as stock options, RSUs, PUs, warrants or convertible securities) that were outstanding during the period, unless the effect is antidilutive.

The calculation of basic and diluted income (loss) per share for the years ended December 31, 2023, 2022 and 2021 is as follows:

	YEAR ENDED DECEMBER 31,
	2023		2022		2021
Net Income (Loss)	$	187,263	$	562,149	$	452,725
Less: Net Income (Loss) Attributable to Noncontrolling Interests	3,029		5,168		2,506
Net Income (Loss) Attributable to Iron Mountain Incorporated (utilized in numerator of Earnings Per Share calculation)	$	184,234	$	556,981	$	450,219
Weighted-average shares—basic	291,936,000		290,812,000		289,457,000
Effect of dilutive potential stock options	1,435,000		1,125,068		645,886
Effect of dilutive potential RSUs and PUs	594,000		507,109		872,204
Weighted-average shares—diluted	293,965,000		292,444,177		290,975,090
Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated:
Basic	$	0.63	$	1.92	$	1.56
Diluted	$	0.63	$	1.90	$	1.55
Antidilutive stock options, RSUs and PUs, excluded from the calculation	81,817		305,527		1,447,722

Y. NEW ACCOUNTING PRONOUNCEMENTS

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS

In December 2021, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers ("ASU 2021-08"). ASU 2021-08 requires that an entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with ASU 2014-09 and for the related revenue contracts in accordance with ASU 2014-09 as if it had originated the contracts. We adopted ASU 2021-08 on January 1, 2023 on a prospective basis, and there was no material impact on our consolidated financial statements.

OTHER AS YET ADOPTED ACCOUNTING PRONOUNCEMENTS

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740), Improvements to Income Tax Disclosures ("ASU 2023-09") to provide disaggregated income tax disclosures on the rate reconciliation and income taxes paid. Further, certain requirements related to uncertain tax positions and unrecognized deferred tax liabilities are eliminated. The amendments in this update should be applied on a prospective basis, with retrospective application permitted. ASU 2023-09 will be effective for us on January 1, 2025, with early adoption permitted. We do not expect ASU 2023-09 to have a material impact on our consolidated financial statements.

In November 2023, the FASB issued ASU No. 2023-07, Improvements to Reportable Segments Disclosures ("ASU 2023-07") to provide more detail in the disclosures for reportable segments. The main provisions of ASU 2023-07 requires (i) enhanced disclosures about significant segment expenses, (ii) extension of certain annual disclosures to interim periods and (iii) certain qualitative information on the chief operating decision maker. The amendments in this update will be effective for us on January 1, 2024, with early adoption permitted. We do not expect ASU 2023-07 to have a material impact on our consolidated financial statements.

In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) ("ASU 2020-04"). ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions, for a limited period of time, to ease the potential burden of recognizing the effects of reference rate reform on financial reporting. The amendments in ASU 2020-04 apply to contracts, hedging relationships and other transactions that reference the London Inter-Bank Offered Rate ("LIBOR") or another reference rate expected to be discontinued due to the global transition away from LIBOR and certain other interbank offered rates. Under ASU 2020-04, an entity could elect to apply the amendments beginning March 12, 2020 through December 31, 2022. In December 2022, the FASB issued ASU No. 2022-06, Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848 ("ASU 2022-06") to defer the sunset date of Topic 848 from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. We are currently evaluating these amendments as they relate to our contracts, hedging relationships and other transactions that reference LIBOR, as well as the impact of ASU 2020-04 and ASU 2022-06 on our consolidated financial statements, but we do not expect the impact to be material.