q12025srpfinal

Supplemental Financial Information First Quarter 2025 investors.ironmountain.com

Table of Contents Section I - Q1 Earnings Press Release Q1 2025 Earnings Press Release 3 Section II - Financial Highlights and Organic Growth Financial and Operating Highlights 6 Organic Revenue Growth 7 Section III - Operational Metrics Global Storage Volume 8 Quarterly Operating Performance 9 Section IV - Balance Sheets, Statements of Operations and Reconciliations Condensed Consolidated Balance Sheets 10 Quarterly Condensed Consolidated Statements of Operations 11 Quarterly Reconciliation of Net Income (Loss) to Adjusted EBITDA 12 Quarterly Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share 13 Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO 14 Section V - Storage and Service Reconciliation Quarterly Storage Rental and Service Business Detail 15 Section VI - Real Estate Metrics Global Real Estate Portfolio and Lease Obligations 16 Facility Lease Expirations 16 Section VII - Data Center Customer and Portfolio Metrics Data Center Customer Lease Expiration and Leasing Activity Summary 17 Data Center Operating Portfolio and Total Potential Capacity 18 Data Center Expansion and Development Activity 19 Section VIII - Capitalization and Debt Maturity Profile Capitalization 20 Total Borrowings Maturity Schedule 20 Debt Maturity Profile 20 Section IX - Capital Expenditures Quarterly Capital Expenditures and Investments 21 Section X - Appendix and Definitions Appendix and Definitions 22 All figures except per share, megawatts (MW), kilowatts (kW), and facility counts in 000s unless noted All figures in reported dollars unless noted Figures may not foot due to rounding All figures for the quarter ended March 31, 2025 unless noted Unaudited investors.ironmountain.com Q1 2025 Supplemental Financial Information 2

Iron Mountain Reports First Quarter 2025 Results • Achieves record quarterly revenue of $1.6 billion, an increase of 7.8% on a reported basis and an increase of 9.4% excluding the effects of foreign exchange • Strong performance across the business, with our growth businesses of data center, digital, and asset lifecycle management (ALM) collectively growing more than 20% • Net Income of $16 million • Delivers record first quarter Adjusted EBITDA of $580 million • Increases 2025 financial guidance PORTSMOUTH, N.H. – May 1, 2025 – Iron Mountain Incorporated (NYSE: IRM), a global leader in information management services, announces financial results for the first quarter of 2025. “We are pleased with our strong start to 2025, delivering another record performance in Revenue, Adjusted EBITDA, and AFFO in the first quarter and above our expectations. Our team’s focus on providing solutions that meet our customers’ needs as part of our Matterhorn growth strategy continues to drive broad based strength across each of our business segments,” said William L. Meaney, President and CEO of Iron Mountain. “Our data center, digital, and ALM businesses are driving strong double digit organic revenue gains and continue to have a long runway for growth. We are increasing our full year guidance based on our strong Q1 performance and positive outlook, and recent changes in currency exchange rates.” Financial Performance Highlights for the First Quarter of 2025 ($ in millions, except per share data) Three Months Ended Y/Y % Change 3/31/25 3/31/24 Reported $ Constant Fx Storage Rental Revenue $948 $885 7% 9% Service Revenue $644 $592 9% 10% Total Revenue $1,593 $1,477 8% 9% Net Income $16 $77 (79)% Reported EPS $0.05 $0.25 (80)% Adjusted EPS $0.43 $0.43 — Adjusted EBITDA $580 $519 12% 13% Adjusted EBITDA Margin 36.4% 35.1% 130 bps AFFO $348 $324 8% AFFO per share $1.17 $1.10 6% • Total reported revenues for the first quarter were $1.6 billion, compared with $1.5 billion in the first quarter of 2024, an increase of 7.8%. Excluding the impact of foreign currency exchange ("Fx"), total reported revenues increased 9.4% compared to the prior year, driven by an 8.8% increase in storage rental revenue and a 10.2% increase in service revenue. • Net Income for the first quarter was $16.2 million, compared with $77.0 million in the first quarter of 2024, primarily driven by the impact of changes in the exchange rates on our intercompany balances. • Adjusted EBITDA for the first quarter was $579.9 million, compared with $518.9 million in the first quarter of 2024, an increase of 11.8%. On a constant currency basis, Adjusted EBITDA increased by 13.5% in the first quarter, compared to the first quarter of 2024, driven by increased revenue in our Global RIM, ALM, and Data Center businesses and improved operating leverage coming from our continued improvement activities. • FFO (Normalized) per share was $0.77 for the first quarter, compared with $0.74 in the first quarter of 2024. Section I - Q1 Earnings Press Release investors.ironmountain.com Q1 2025 Supplemental Financial Information 3

• AFFO was $348.4 million for the first quarter, compared with $323.7 million in the first quarter of 2024, an increase of 7.6% driven by improved Adjusted EBITDA. • AFFO per share was $1.17 for the first quarter, compared with $1.10 in the first quarter of 2024. Dividend On May 1, 2025, Iron Mountain's Board of Directors declared a quarterly cash dividend of $0.785 per share of common stock for the second quarter. The second quarter 2025 dividend is payable on July 3, 2025, to shareholders of record at the close of business on June 16, 2025. Guidance Iron Mountain increased full year 2025 guidance; details are summarized in the table below. 2025 Guidance(1) ($ in millions, except per share data) New Approximate Y/Y % Change at Midpoint Previous Approximate Y/Y % Change at Midpoint Total Revenue $6,740 - $6,890 ~11% $6,650 - $6,800 ~9% Adjusted EBITDA $2,505 - $2,555 ~13% $2,475 - $2,525 ~12% AFFO $1,480 - $1,510 ~11% $1,450 - $1,480 ~9% AFFO Per Share $4.95 - $5.05 ~10% $4.85 - $4.95 ~8% (1) Iron Mountain does not provide a reconciliation of non-GAAP measures that it discusses as part of its annual guidance or long term outlook because certain significant information required for such reconciliation is not available without unreasonable efforts or at all, including, most notably, the impact of exchange rates on Iron Mountain’s transactions, loss or gain related to the disposition of real estate and other income or expense. Without this information, Iron Mountain does not believe that a reconciliation would be meaningful. Q1 2025 Earnings Conference Call and Related Materials The conference call / webcast details, earnings presentation and supplemental financial information, which includes definitions of certain capitalized terms used in this release, are available on Iron Mountain’s Investor Relations website. About Iron Mountain Iron Mountain Incorporated (NYSE: IRM) is trusted by more than 240,000 customers in 61 countries, including approximately 95% of the Fortune 1000, to help unlock value and intelligence from their assets through services that transcend the physical and digital worlds. Our broad range of solutions address their information management, digital transformation, information security, data center and asset lifecycle management needs. Our longstanding commitment to safety, security, sustainability and innovation in support of our customers underpins everything we do. To learn more about Iron Mountain, please visit www.IronMountain.com. Investor Relations Contacts: Mark Rupe Erika Crabtree SVP, Investor Relations Manager, Investor Relations [email protected] [email protected] (215) 402-7013 (617) 535-2845 Section I - Q1 Earnings Press Release investors.ironmountain.com Q1 2025 Supplemental Financial Information 4

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: We have made statements in this press release that constitute "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995 and other securities laws. These forward-looking statements concern our current expectations regarding our future results from operations, economic performance, financial condition, goals, strategies, investment objectives, plans and achievements. These forward-looking statements are subject to various known and unknown risks, uncertainties and other factors, and you should not rely upon them except as statements of our present intentions and of our present expectations, which may or may not occur. When we use words such as “believes”, “expects”, “anticipates”, “estimates”, “plans”, “intends”, “projects”, “pursue”, “will” or similar expressions, we are making forward- looking statements. Although we believe that our forward-looking statements are based on reasonable assumptions, our expected results may not be achieved, and actual results may differ materially from our expectations. In addition, important factors that could cause actual results to differ from expectations include, among others: (i) our ability or inability to execute our strategic growth plan, including our ability to invest according to plan, grow our businesses (including through joint ventures or other co-investment vehicles), incorporate alternative technologies (including artificial intelligence) into our offerings, achieve satisfactory returns on new product offerings, continue our revenue management, expand and manage our global operations, complete acquisitions on satisfactory terms, integrate acquired companies efficiently and transition to more sustainable sources of energy; (ii) changes in customer preferences and demand for our storage and information management services, including as a result of the shift from paper and tape storage to alternative technologies that require less physical space; (iii) the costs of complying with and our ability to comply with laws, regulations and customer requirements, including those relating to data privacy and cybersecurity issues, as well as fire and safety and environmental standards; (iv) the impact of attacks on our internal information technology (“IT”) systems, including the impact of such incidents on our reputation and ability to compete and any litigation or disputes that may arise in connection with such incidents; (v) our ability to fund capital expenditures; (vi) the impact of our distribution requirements on our ability to execute our business plan; (vii) our ability to remain qualified for taxation as a real estate investment trust for United States federal income tax purposes; (viii) changes in the political and economic environments in the countries in which we operate and changes in the global political climate; (ix) our ability to raise debt or equity capital and changes in the cost of our debt; (x) our ability to comply with our existing debt obligations and restrictions in our debt instruments; (xi) the impact of service interruptions or equipment damage and the cost of power on our data center operations; (xii) the cost or potential liabilities associated with real estate necessary for our business; (xiii) unexpected events, including those resulting from climate change or geopolitical events, could disrupt our operations and adversely affect our reputation and results of operations; (xiv) failures to implement and manage new IT systems; (xv) other trends in competitive or economic conditions affecting our financial condition or results of operations not presently contemplated; and (xvi) the other risks described in our periodic reports filed with the SEC, including under the caption “Risk Factors” in Part I, Item 1A of our Annual Report. Except as required by law, we undertake no obligation to update any forward-looking statements appearing in this press release. Reconciliation of Non-GAAP Measures Throughout this press release, Iron Mountain discusses (1) Adjusted EBITDA, (2) Adjusted EPS, (3) FFO (Nareit), (4) FFO (Normalized), and (5) AFFO. These measures do not conform to accounting principles generally accepted in the United States (“GAAP”). These non-GAAP measures are supplemental metrics designed to enhance our disclosure and to provide additional information that we believe to be important for investors to consider in addition to, but not as a substitute for, other measures of financial performance reported in accordance with GAAP, such as operating income, net income (loss) attributable to Iron Mountain Incorporated or cash flows from operating activities (as determined in accordance with GAAP). The reconciliation of these measures to the appropriate GAAP measure, as required by Regulation G under the Securities Exchange Act of 1934, as amended, and their definitions are included later in this release. Section I - Q1 Earnings Press Release investors.ironmountain.com Q1 2025 Supplemental Financial Information 5

Financial Highlights Q1 2025 Q4 2024 Q3 2024 Q2 2024 Q1 2024 Storage Rental Revenue $948,376 $941,970 $935,701 $919,746 $884,842 Service Revenue $644,153 $639,309 $621,657 $614,663 $592,021 Total Revenues $1,592,529 $1,581,279 $1,557,358 $1,534,409 $1,476,863 Adjusted EBITDA $579,906 $605,051 $568,113 $544,361 $518,855 Adjusted EBITDA Margin 36.4 % 38.3 % 36.5 % 35.5 % 35.1 % Net Income (Loss) Attributable to Iron Mountain Incorporated $15,952 $103,932 $(33,620) $35,783 $74,061 Reported EPS - Fully Diluted $0.05 $0.35 ($0.11) $0.12 $0.25 Adjusted EPS $0.43 $0.50 $0.44 $0.42 $0.43 FFO (Normalized) $229,070 $252,468 $233,269 $231,021 $219,777 FFO (Normalized) per Share $0.77 $0.85 $0.79 $0.78 $0.74 AFFO $348,400 $367,986 $332,000 $320,901 $323,653 AFFO per Share $1.17 $1.24 $1.13 $1.08 $1.10 TTM AFFO Payout Ratio 62.0 % 60.0 % 60.3 % 60.3 % 61.0 % Dividend per Share $0.79 $0.72 $0.72 $0.65 $0.65 Weighted Average Common Shares Outstanding - Diluted 297,260 297,201 293,603 295,838 295,221 Net Lease-Adjusted Leverage Ratio 5.0x 5.0x 5.0x 5.0x 5.1x Operating Highlights Q1 2025 Q4 2024 Q3 2024 Q2 2024 Q1 2024 Organic Storage Rental Revenue Growth 8.8 % 8.8 % 9.3 % 10.1 % 7.5 % Organic Service Revenue Growth 7.1 % 7.0 % 10.0 % 9.4 % 9.6 % Total Volume - Storage 734,166 733,571 732,997 732,607 732,031 Storage Facility Capacity Utilization 79.9 % 79.6 % 79.4 % 79.2 % 79.2 % Records Management Retention Rate 92.9 % 92.6 % 92.7 % 92.8 % 92.9 % Storage Revenue / Sq. Ft. $10.14 $10.07 $9.92 $9.74 $9.38 Storage NOI / Sq. Ft. $8.10 $8.14 $7.95 $7.75 $7.46 Data Center: Leasable Megawatts 424.2 416.2 364.7 265.7 261.4 Leased % - Stabilized 98.0 % 97.4 % 98.7 % 96.0 % 95.7 % Leased % - Total 96.1 % 95.5 % 96.8 % 93.5 % 94.0 % Kilowatts Leased - New/Expansion 3,700 9,664 9,205 66,493 30,449 Churn 0.3 % 4.4 % 0.5 % 1.2 % 0.9 % Number of Facilities 29 29 28 26 26 Number of Markets 21 21 21 21 21 Section II - Financial Highlights and Organic Growth investors.ironmountain.com Q1 2025 Supplemental Financial Information 6

Organic Revenue Growth (1) Q1 2025 Reported Constant Currency Organic Revenue Storage Rental 7.2% 8.8% 8.8% Service 8.8% 10.2% 7.1% Total Revenues 7.8% 9.4% 8.1% Total Organic Revenue Growth 5.7% 5.5% 8.7% 8.3% 9.8% 9.5% 8.1% 8.1% Q2 2023 Q3 2023 Q4 2023 Q1 2024 Q2 2024 Q3 2024 Q4 2024 Q1 2025 0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% Organic Storage Rental Revenue Growth 10.8% 9.7% 10.4% 7.5% 10.1% 9.3% 8.8% 8.8% Q2 2023 Q3 2023 Q4 2023 Q1 2024 Q2 2024 Q3 2024 Q4 2024 Q1 2025 6.0% 8.0% 10.0% 12.0% Organic Service Revenue Growth (1.4)% (0.6)% 6.2% 9.6% 9.4% 10.0% 7.0% 7.1% Q2 2023 Q3 2023 Q4 2023 Q1 2024 Q2 2024 Q3 2024 Q4 2024 Q1 2025 (4.0)% 0.0% 4.0% 8.0% 12.0% (1) Constant Currency and excluding impact from business acquisitions and divestitures. Section II - Financial Highlights and Organic Growth investors.ironmountain.com Q1 2025 Supplemental Financial Information 7

Global Storage Volume Global RIM Corporate and Other Q4 2022 Q1 2023 Q2 2023 Q3 2023 Q4 2023 Q1 2024 Q2 2024 Q3 2024 Q4 2024 Q1 2025 700,000 710,000 720,000 730,000 740,000 Q4 2022 Q1 2023 Q2 2023 Q3 2023 Q4 2023 Q1 2024 Q2 2024 Q3 2024 Q4 2024 Q1 2025 Global RIM 724,480 724,926 725,510 (1) 725,907 726,048 726,316 726,712 726,952 727,266 727,496 Corporate and Other 4,804 5,210 5,256 5,356 5,493 5,715 5,895 6,045 6,305 6,671 Total Volume - Storage 729,284 730,136 730,767 731,263 731,541 732,031 732,607 732,997 733,571 734,166 Business acquisitions during the quarter (2) — — — — — — — — — — (1) On June 29, 2023, we acquired 100% interest in Clutter Intermediate, Inc. and control of all assets of the related Clutter joint venture, of which we had a preexisting relationship. The volume associated with this business both prior and subsequent to our acquisition is substantially consistent. (2) Volume acquired through acquisition in the quarter; this is included in Total Storage Volume. Section III - Operational Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 8

Quarterly Operating Performance Y/Y % Change Q1 2025 Q4 2024 Q1 2024 Reported Constant Currency Organic Growth (1) Global RIM Business Storage Rental $757,508 $755,972 $728,984 3.9% 5.7% 5.7% Service 498,434 502,374 481,173 3.6% 5.1% 5.1% Total Revenues $1,255,942 $1,258,346 $1,210,157 3.8% 5.5% 5.5% Adjusted EBITDA $556,314 $579,113 $526,268 Adjusted EBITDA Margin 44.3 % 46.0 % 43.5 % Global Data Center Business Storage Rental $172,945 $168,073 $140,028 23.5% 24.4% 24.4% Service 252 2,110 3,909 (93.6)% (93.5)% (93.5)% Total Revenues $173,197 $170,183 $143,937 20.3% 21.2% 21.2% Adjusted EBITDA $90,816 $88,132 $61,568 Adjusted EBITDA Margin 52.4 % 51.8 % 42.8 % Corporate and Other Storage Rental $17,923 $17,925 $15,830 13.2% 13.4% 13.4% Service 145,467 134,825 106,939 36.0% 36.6% 19.5% Total Revenues $163,390 $152,750 $122,769 33.1% 33.6% 18.7% Adjusted EBITDA $(67,224) $(62,194) $(68,981) Total Consolidated Storage Rental $948,376 $941,970 $884,842 7.2% 8.8% 8.8% Service 644,153 639,309 592,021 8.8% 10.2% 7.1% Total Revenues $1,592,529 $1,581,279 $1,476,863 7.8% 9.4% 8.1% Adjusted EBITDA $579,906 $605,051 $518,855 Adjusted EBITDA Margin 36.4 % 38.3 % 35.1 % (1) Constant Currency and excluding impact from business acquisitions and divestitures. Section III - Operational Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 9

Condensed Consolidated Balance Sheets 3/31/2025 12/31/2024 ASSETS Current Assets: Cash and Cash Equivalents $155,338 $155,716 Accounts Receivable, Net 1,312,079 1,291,379 Prepaid Expenses and Other 282,945 244,127 Total Current Assets $1,750,362 $1,691,222 Property, Plant and Equipment: Property, Plant and Equipment $12,758,467 $11,985,997 Less: Accumulated Depreciation (4,509,307) (4,354,398) Property, Plant and Equipment, Net $8,249,160 $7,631,599 Other Assets, Net: Goodwill $5,141,810 $5,083,817 Customer and Supplier Relationships and Other Intangible Assets 1,266,993 1,274,731 Operating Lease Right-of-Use Assets 2,386,511 2,489,893 Other 567,251 545,853 Total Other Assets, Net $9,362,565 $9,394,294 Total Assets $19,362,087 $18,717,115 LIABILITIES AND EQUITY Current Liabilities: Current Portion of Long-term Debt $736,922 $715,109 Accounts Payable 707,581 678,716 Accrued Expenses and Other Current Liabilities 1,063,237 1,366,568 Deferred Revenue 333,171 326,882 Total Current Liabilities $2,840,911 $3,087,275 Long-term Debt, Net of Current Portion 14,177,474 13,003,977 Long-term Operating Lease Liabilities, Net of Current Portion 2,224,080 2,334,826 Other Long-term Liabilities 339,144 312,199 Deferred Income Taxes 204,516 205,341 Redeemable Noncontrolling Interests 78,237 78,171 Total Long-term Liabilities $17,023,451 $15,934,514 Total Liabilities $19,864,362 $19,021,789 (Deficit) Equity Total (Deficit) Equity $(502,275) $(304,674) Total Liabilities and (Deficit) Equity $19,362,087 $18,717,115 Section IV - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q1 2025 Supplemental Financial Information 10

Quarterly Condensed Consolidated Statements of Operations Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Revenues: Storage Rental $948,376 $941,970 0.7 % $884,842 7.2 % Service 644,153 639,309 0.8 % 592,021 8.8 % Total Revenues $1,592,529 $1,581,279 0.7 % $1,476,863 7.8 % Operating Expenses: Cost of Sales (excluding Depreciation and Amortization) $710,204 $688,933 3.1 % $653,255 8.7 % Selling, General and Administrative 329,737 333,307 (1.1) % 319,465 3.2 % Depreciation and Amortization 232,154 234,609 (1.0) % 209,555 10.8 % Acquisition and Integration Costs 5,823 7,269 (19.9) % 7,809 (25.4) % Restructuring and Other Transformation 54,746 36,797 48.8 % 40,767 34.3 % Loss (Gain) on Disposal/Write-Down of PP&E, Net 5,571 (2,074) n/a 389 n/a Total Operating Expenses $1,338,235 $1,298,841 3.0 % $1,231,240 8.7 % Operating Income (Loss) $254,294 $282,438 (10.0) % $245,623 3.5 % Interest Expense, Net 194,738 194,452 0.1 % 164,519 18.4 % Other Expense (Income), Net 28,488 (36,243) (178.6) % (12,530) n/a Net Income (Loss) Before Provision (Benefit) for Income Taxes $31,068 $124,229 (75.0) % $93,634 (66.8) % Provision (Benefit) for Income Taxes 14,835 18,544 (20.0) % 16,609 (10.7) % Net Income (Loss) $16,233 $105,685 (84.6) % $77,025 (78.9) % Less: Net Income (Loss) Attributable to Noncontrolling Interests 281 1,753 (84.0) % 2,964 (90.5) % Net Income (Loss) Attributable to Iron Mountain Incorporated $15,952 $103,932 (84.7) % $74,061 (78.5) % Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated: Basic $0.05 $0.35 (85.7) % $0.25 (80.0) % Diluted $0.05 $0.35 (85.7) % $0.25 (80.0) % Weighted Average Common Shares Outstanding - Basic 294,507 293,771 0.3 % 292,746 0.6 % Weighted Average Common Shares Outstanding - Diluted 297,260 297,201 — 295,221 0.7 % Section IV - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q1 2025 Supplemental Financial Information 11

Quarterly Reconciliation of Net Income (Loss) to Adjusted EBITDA Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Net Income (Loss) $16,233 $105,685 (84.6) % $77,025 (78.9) % Add / (Deduct): Interest Expense, Net 194,738 194,452 0.1 % 164,519 18.4 % Provision (Benefit) for Income Taxes 14,835 18,544 (20.0) % 16,609 (10.7) % Depreciation and Amortization 232,154 234,609 (1.0) % 209,555 10.8 % Acquisition and Integration Costs 5,823 7,269 (19.9) % 7,809 (25.4) % Restructuring and Other Transformation 54,746 36,797 48.8 % 40,767 34.3 % Loss (Gain) on Disposal/Write-Down of PP&E, Net (Including Real Estate) 5,571 (2,074) n/a 389 n/a Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 27,382 (37,795) (172.4) % (13,110) n/a Stock-Based Compensation Expense 26,094 44,647 (41.6) % 14,039 85.9 % Our Share of Adjusted EBITDA Reconciling Items from our Unconsolidated Joint Ventures 2,330 2,917 (20.1) % 1,253 86.0 % Adjusted EBITDA $579,906 $605,051 (4.2) % $518,855 11.8 % Section IV - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q1 2025 Supplemental Financial Information 12

Quarterly Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.05 $0.35 (85.7) % $0.25 (80.0) % Add / (Deduct): Acquisition and Integration Costs 0.02 0.02 — 0.03 (33.3) % Restructuring and Other Transformation 0.18 0.12 50.0 % 0.14 28.6 % Loss (Gain) on Disposal/Write-Down of PP&E, Net 0.02 (0.01) n/a — n/a Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 0.09 (0.13) (169.2) % (0.04) n/a Stock-Based Compensation Expense 0.09 0.15 (40.0) % 0.05 80.0 % Non-Cash Amortization Related to Derivative Instruments 0.01 0.01 — 0.01 — Tax Impact of Reconciling Items and Discrete Tax Items (1) (0.04) (0.03) 33.3 % (0.01) n/a Income (Loss) Attributable to Noncontrolling Interests — 0.01 (100.0) % 0.01 (100.0) % Adjusted EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.43 $0.50 (14.0) % $0.43 — (1) The difference between our effective tax rates and our structural tax rate (or adjusted effective tax rates) for the three months ended March 31, 2025, March 31, 2024 and December 31, 2024 is primarily due to (i) the reconciling items above, which impact our reported net income (loss) before provision (benefit) for income taxes but have an insignificant impact on our reported provision (benefit) for income taxes and (ii) other discrete tax items. Our structural tax rate for purposes of the calculation of Adjusted EPS for the quarters ended March 31, 2025 and 2024 was 17.0% and 13.9% respectively, and quarter ended December 31, 2024 was 15.6%. The Tax Impact of Reconciling Items and Discrete Tax Items was calculated using the current quarter’s estimate of the annual structural tax rate. This may result in the current period adjustment plus prior reported quarterly adjustments not summing to the full year adjustment. Section IV - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q1 2025 Supplemental Financial Information 13

Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Net Income (Loss) $16,233 $105,685 (84.6) % $77,025 (78.9) % Add / (Deduct): Real Estate Depreciation (1) 94,147 92,154 2.2 % 83,573 12.7 % Loss (Gain) on Sale of Real Estate, Net of Tax 312 (6,614) (104.7) % (1,194) (126.1) % Data Center Lease-Based Intangible Assets Amortization (2) 2,019 5,553 (63.6) % 5,576 (63.8) % Our Share of FFO (Nareit) Reconciling Items from our Unconsolidated Joint Ventures 1,496 1,855 (19.4) % 441 n/a FFO (Nareit) $114,207 $198,633 (42.5) % $165,421 (31.0) % Add / (Deduct): Acquisition and Integration Costs 5,823 7,269 (19.9) % 7,809 (25.4) % Restructuring and Other Transformation 54,746 36,797 48.8 % 40,767 34.3 % Loss (Gain) on Disposal/Write-Down of PP&E, Net (Excluding Real Estate) 5,292 5,442 (2.8) % 1,818 191.1 % Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 27,382 (37,795) (172.4) % (13,110) n/a Stock-Based Compensation Expense 26,094 44,647 (41.6) % 14,039 85.9 % Non-Cash Amortization Related to Derivative Instruments 4,176 4,176 — 4,176 — Real Estate Financing Lease Depreciation 3,148 3,221 (2.3) % 2,986 5.4 % Tax Impact of Reconciling Items and Discrete Tax Items (3) (11,673) (9,997) 16.8 % (4,170) 179.9 % Our Share of FFO (Normalized) Reconciling Items from our Unconsolidated Joint Ventures (125) 75 n/a 41 n/a FFO (Normalized) $229,070 $252,468 (9.3) % $219,777 4.2 % Add / (Deduct): Non-Real Estate Depreciation 65,146 67,016 (2.8) % 57,073 14.1 % Amortization Expense (4) 67,694 66,665 1.5 % 60,346 12.2 % Amortization of Deferred Financing Costs 7,856 6,671 17.8 % 6,100 28.8 % Revenue Reduction Associated with Amortization of Customer Inducements and Above- and Below-Market Leases 1,317 1,229 7.2 % 1,322 (0.4) % Non-Cash Rent Expense (Income) 3,225 4,741 (32.0) % 5,659 (43.0) % Reconciliation to Normalized Cash Taxes 1,999 5,034 (60.3) % 1,931 3.5 % Our Share of AFFO Reconciling Items from our Unconsolidated Joint Ventures 176 179 (1.7) % 182 (3.3) % Less: Recurring Capital Expenditures 28,083 36,017 (22.0) % 28,737 (2.3) % AFFO $348,400 $367,986 (5.3) % $323,653 7.6 % Per Share Amounts (Fully Diluted Shares): FFO (Nareit) $0.38 $0.67 (43.3) % $0.56 (32.1) % FFO (Normalized) $0.77 $0.85 (9.4) % $0.74 4.1 % AFFO Per Share $1.17 $1.24 (5.6) % $1.10 6.4 % Weighted Average Common Shares Outstanding - Basic 294,507 293,771 0.3 % 292,746 0.6 % Weighted Average Common Shares Outstanding - Diluted 297,260 297,201 — 295,221 0.7 % (1) Includes depreciation expense related to owned real estate assets (land improvements, buildings, building and leasehold improvements, data center infrastructure and racking structures), excluding depreciation related to real estate financing leases. (2) Includes amortization expense for Data Center In-Place Lease Intangible Assets and Data Center Tenant Relationship Intangible Assets. (3) Represents the tax impact of (i) the reconciling items above, which impacts our reported net income (loss) before provision (benefit) for income taxes but have an insignificant impact on our reported provision (benefit) for income taxes and (ii) other discrete tax items. (4) Includes customer and supplier relationship value, intake costs, acquisition of customer relationships, capitalized commissions and other intangibles. Section IV - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q1 2025 Supplemental Financial Information 14

Quarterly Storage Rental and Service Business Detail Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Storage Rental Business Detail Total Storage Rental Revenue $948,376 $941,970 0.7 % $884,842 7.2 % Plus: Terminations/Permanent Withdrawal Fees 7,875 10,616 (25.8) % 9,664 (18.5) % Total Revenue from Adjusted Storage Rental Activities $956,251 $952,586 0.4 % $894,506 6.9 % Less: Storage Rental Expenses Storage Rent 121,506 123,459 (1.6) % 123,389 (1.5) % Storage Rental Labor 9,983 8,662 15.3 % 10,260 (2.7) % All Other Storage Costs 149,478 144,065 3.8 % 136,828 9.2 % Storage Rental Cost of Sales $280,966 $276,186 1.7 % $270,477 3.9 % Storage Rental Gross Profit $675,285 $676,401 (0.2) % $624,029 8.2 % Storage Rental Gross Margin 70.6 % 71.0 % -40 bps 69.8 % 90 bps Service Business Detail Total Service Revenue $644,153 $639,309 0.8 % $592,021 8.8 % Less: Terminations/Permanent Withdrawal Fees 7,875 10,616 (25.8) % 9,664 (18.5) % Total Revenue from Adjusted Service Activities $636,278 $628,693 1.2 % $582,357 9.3 % Less: Service Expenses Service Rent 7,886 7,815 0.9 % 6,217 26.8 % Service Labor 263,998 263,908 — 241,071 9.5 % All Other Service Costs 157,353 141,024 11.6 % 135,490 16.1 % Service Cost of Sales $429,238 $412,747 4.0 % $382,778 12.1 % Service Gross Profit $207,040 $215,946 (4.1) % $199,579 3.7 % Service Gross Margin 32.5 % 34.3 % -180 bps 34.3 % -180 bps Section V - Storage and Service Reconciliation investors.ironmountain.com Q1 2025 Supplemental Financial Information 15

Global Real Estate Portfolio and Lease Obligations Global Real Estate Portfolio (1) Owned Facilities Leased Facilities Total Buildings Sq. Ft. Buildings Sq. Ft. Buildings Sq. Ft. Total as of 12/31/2024 236 24,171 1,110 73,909 1,346 98,079 Additions & Expansions 1 45 20 805 21 850 Dispositions & Move Outs — — (27) (1,027) (27) (1,027) Total as of 03/31/2025 (2) 237 24,216 1,103 73,687 1,340 97,902 Total % 17.7 % 24.7 % 82.3 % 75.3 % Top Five Markets Owned, United States (in Sq. Ft.) Top Five Markets Owned, International (in Sq. Ft.) Northern New Jersey 1,962 Paris, France 807 Chicago 1,282 Montreal, Canada 552 Boston 1,083 Mexico City, Mexico 452 Dallas 966 Toronto, Canada 434 Houston 873 Lima, Peru 434 Facility Lease Expirations (3) (% of total square feet subject to lease) 3.8% 6.2% 2.6% 4.3% 3.9% 4.4% 5.8% 3.2% 4.0% 62.0% 2025 2026 2027 2028 2029 2030 2031 2032 2033 Thereafter Weighted-Average Remaining Operating Lease Obligation: 10.8 Years (1) Includes real estate held in consolidated joint ventures. (2) Includes 15 owned data center facilities and 5 leased data center facilities with 3.3M Sq. Ft. and 0.8M Sq. Ft., respectively. (3) Includes financing and operating lease obligations. Section VI - Real Estate Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 16

Data Center Customer Lease Expiration Year Number of Leases Expiring Total MW Expiring Percentage of Total MW Annualized GAAP TCV Rent Expiring Percentage of TCV Annualized Rent 2025 632 22.5 4.2% 57,575 6.9% 2026 604 30.2 5.6% 80,444 9.7% 2027 208 20.1 3.7% 62,775 7.6% 2028 173 40.6 7.6% 80,127 9.7% 2029 72 51.1 9.5% 54,339 6.6% 2030 37 57.7 10.8% 73,507 8.9% 2031 4 2.3 0.4% 4,595 0.6% Thereafter 30 311.9 58.2% 415,940 49.9% Total 1,760 536.4 100.0% $829,300 100.0% WALE: 10.1 years Data Center Leasing Activity Summary Q1 2025 Transaction Count GAAP MRR kW $ / kW / Month New/expansion leases signed 116 $721 3,700 $195 Commenced leases 95 1,831 11,666 157 Commenced Built to Suit leases — — — — Renewed leases 287 2,979 9,509 313 Churn 0.3% Cash Mark to Market 18.7% GAAP Mark to Market 26.5% AZP-3 Rendering Section VII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 17

Data Center Operating Portfolio Stabilized Pre-Stabilized Total Leaseable MW Leased % by MW Leaseable MW Leased % by MW Leaseable MW Leased % by MW Boyers and Other WPA-1 and Other 14.2 74.9% — — 14.2 74.9% Phoenix AZP-1 41.0 100.0% — — 41.0 100.0% AZP-2 46.5 100.0% — — 46.5 100.0% Scottsdale AZS-1 5.7 100.0% — — 5.7 100.0% Denver DEN-1 11.3 88.9% — — 11.3 88.9% New Jersey NJE-1 16.8 85.9% 4.0 62.5% 20.8 81.3% Northern Virginia VA-1 12.4 100.0% — — 12.4 100.0% VA-2 36.0 100.0% — — 36.0 100.0% VA-3 44.0 100.0% — — 44.0 100.0% VA-4 (1) 32.0 100.0% — — 32.0 100.0% VA-5 (1) 40.0 100.0% — — 40.0 100.0% VA-6 Phase 1 (2) 24.0 100.0% — — 24.0 100.0% Amsterdam AMS-1 13.1 96.8% — — 13.1 96.8% London LON-1 8.7 96.3% — — 8.7 96.3% LON-2 18.0 100.0% — — 18.0 100.0% Frankfurt FRA-1 (3) 27.0 100.0% — — 27.0 100.0% FRA-2 9.8 100.0% — — 9.8 100.0% Singapore SIN-1 6.8 100.0% — — 6.8 100.0% Madrid MAD-1 1.0 45.0% — — 1.0 45.0% India Web Werks 1.5 100.0% 10.4 35.0% 11.9 43.3% Total Data Center Properties 409.8 98.0% 14.4 42.7% 424.2 96.1% (1) VA-4/5 are held by a consolidated joint venture. (2) VA-6 data center is held by a consolidated joint venture. (3) FRA-1 data center is an unconsolidated joint venture. Total Potential Capacity - Megawatts Q1 2025 Q1 2024 Operating Portfolio 424.2 261.4 Under Construction 184.5 233.7 Held for Development 671.2 365.7 Total Data Center Portfolio 1,279.9 860.8 Section VII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 18

Data Center Expansion and Development Activity Project / Facilities MW Under Construction MW Pre- leased % Pre- Leased Investment in Q1 2025 ($M) Cumulative Investment ($M) Total Expected Investment ($M) (3) Expected Completion Expected Stabilization MW Held for Development Data Center Expansion Amsterdam AMS-1 Phase 4 5.0 — — $0.4 $44.5 $45.0 Q2 2027 Q2 2028 5.0 Madrid MAD-1 Phase 1 2.0 0.3 14.0% $0.7 $26.4 $31.9 Q3 2025 Q3 2026 — India Web Werks 2.5 — — — — — 2.9 All Other Facilities (1) 1.0 1.0 — — — — 20.4 Total Expansion 10.5 1.3 12.2% $1.1 $70.8 $76.9 28.3 New Development Phoenix AZP-3 Phase 1 18.0 18.0 100.0% $45.3 $177.5 $297.5 Q4 2025 Q4 2025 — AZP-3 Phase 2 10.0 10.0 100.0% $14.8 $29.8 $60.1 Q2 2026 Q2 2026 — AZP-3 Phase 3 8.0 8.0 100.0% $14.1 $20.7 $47.4 Q3 2026 Q3 2026 — Amsterdam AMS-2 — — — — — — 20.0 Chicago CHI-2 Phase 1 12.0 — — $47.4 $144.9 $195.4 Q4 2025 Q4 2026 — CHI-2 Future Phases — — — — — — 24.0 London LON-2 Phase 3 9.0 9.0 100.0% $4.2 $64.5 $70.1 Q2 2025 Q2 2025 — LON-3 Future Phases 25.0 25.0 100.0% $48.8 $80.5 $391.9 Q4 2026 Q4 2026 — Madrid MAD-1 Future Phases — — — — — — 76.0 Northern Virginia VA-6 Phase 2 (2) 8.0 7.0 87.5% $17.8 $57.0 $64.4 Q2 2025 Q2 2025 — VA-7 Phase 1 (2) 18.0 18.0 100.0% $56.3 $228.6 $265.1 Q2 2025 Q2 2025 — VA-7 Phase 2 (2) 18.0 18.0 100.0% $63.0 $72.1 $108.9 Q4 2025 Q4 2025 — VA Future Phases (1) 32.0 32.0 100.0% — — — 174.0 India Web Werks — — — — — — 148.9 Miami MIA-1 16.0 — — $11.7 $21.5 $193.0 Q3 2026 Q3 2026 — Richmond RIC Future Phases — — — — — — 200.0 Total New Development 174.0 145.0 83.3% $323.3 $897.1 $1,693.7 642.9 Total Development 184.5 146.3 79.3% $324.4 $967.9 $1,770.6 671.2 (1) Includes megawatts pre-leased where construction is planned, but has not commenced. (2) VA-6 and VA-7 are held by a consolidated joint venture; construction costs are funded by the joint venture with Iron Mountain managing the construction. (3) Excludes cost associated with megawatts pre-leased where facility construction is planned, but has not commenced. Section VII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q1 2025 Supplemental Financial Information 19

Capitalization Revolving Credit Facility and Term Loan A Total Market Capitalization as of 03/31/2025 Capacity $2,963,281 # of Shares Outstanding 294,969 Outstanding $1,286,281 Share Price as of 03/31/25 $86.04 Letters of Credit $7,406 Total Market Capitalization $25,379,110 Remaining Capacity $1,669,594 Net Debt (1) $14,869,026 Interest Rate Spread (Prime) 0.75 % Total Enterprise Value $40,248,136 Interest Rate Spread (SOFR) 1.75 % Net Debt to Total Enterprise Value 36.9 % Weighted Average Interest Rate 6.46 % Adjusted EBITDA to Interest Expense 3.0x Maturity Date 3/18/2030 Total Enterprise Value to Adjusted EBITDA (2) 17.5x Credit Facility Fixed Charge Coverage Ratio 2.4x Net Total Lease-Adjusted Leverage Ratio 5.0x Fixed vs. Floating Rate Debt 80% 20% Fixed Rate Debt Floating Rate Debt Credit Rating S&P Moody's Corporate BB- Ba3 Senior Credit Facility BB Ba3 Outlook Stable Stable Latest Update 12/3/2024 10/10/2024 Total Long Term Debt Weighted Average Rates Weighted Average Interest 5.7 % Weighted Average Maturity 4.6 Years USD denominated 90 % Debt Maturity Profile ($ in Millions) (3) (4) 691 705 1,722 1,363 2,057 2,553 2,839 1,350 1,200 24 18 Revolving Credit Facility and Term Loan A Bi-Lateral Loans Construction Loans IMDC AUD Term Loan B A/R Securitization USD Term Loan B (2031) Mortgage Notes Payable Senior Unsecured Notes 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2036 (1) Net debt is calculated as current portion of long-term debt of $736.9M plus long-term debt net of current portion of $14,177.5M plus deferred financing costs of $110.0M less cash and cash equivalents of $155.3M. (2) Total Enterprise Value to Adjusted EBITDA is calculated on a trailing twelve-month basis. (3) Excludes Deferred Financing Costs, Discounts, Financing Leases, Notes Payable and Other. (4) In addition to the above, the Company has approximately $293.4M of undrawn committed asset level financing for the construction of four Data Center assets in Northern Virginia. Section VIII - Capitalization and Debt Maturity Profile investors.ironmountain.com Q1 2025 Supplemental Financial Information 20

Quarterly Capital Expenditures Q1 2025 Q4 2024 Q/Q % Change Q1 2024 Y/Y % Change Growth: Data Center $575,999 $541,879 6.3 % $276,631 108.2 % Real Estate 30,934 73,419 (57.9) % 46,755 (33.8) % Innovation and Other 21,584 69,843 (69.1) % 13,730 57.2 % Total Growth Capital Expenditures $628,517 $685,141 (8.3) % $337,116 86.4 % Recurring: Data Center $3,067 $6,486 (52.7) % $1,768 73.5 % Real Estate 8,196 17,031 (51.9) % 9,361 (12.4) % Non-Real Estate 16,820 12,500 34.6 % 17,608 (4.5) % Total Recurring Capital Expenditures $28,083 $36,017 (22.0) % $28,737 (2.3) % Total Growth and Recurring Capital Expenditures $656,600 $721,158 (9.0) % $365,853 79.5 % Net Change in Prepaid and Accrued Capital Expenditures 18,167 (103,562) (117.5) % 15,292 18.8 % Total Cash Paid for Growth and Recurring Capital Expenditures $674,767 $617,596 9.3 % $381,145 77.0 % Section IX - Capital Expenditures investors.ironmountain.com Q1 2025 Supplemental Financial Information 21

Non-GAAP Measures and Definitions Non-GAAP measures are supplemental metrics designed to enhance our disclosures and to provide additional information that we believe to be important for investors to consider when evaluating our financial performance. These non-GAAP measures should be considered in addition to, but not as a substitute for, other measures of financial performance reported in accordance with accounting principles generally accepted in the United States of America (“GAAP”), such as operating income, income (loss) from continuing operations, net income (loss) or cash flows from operating activities from continuing operations (as determined in accordance with GAAP). SRP FLS Statement: We have made statements in this Supplemental Financial Information that constitute "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995 and other securities laws. These forward-looking statements concern our current expectations regarding our future results from operations, economic performance, financial condition, goals, strategies, investment objectives, plans and achievements. These forward-looking statements are subject to various known and unknown risks, uncertainties and other factors, and you should not rely upon them except as statements of our present intentions and of our present expectations, which may or may not occur. When we use words such as “believes”, “expects”, “anticipates”, “estimates”, “plans”, “intends”, "projects", “pursue”, “will” or similar expressions, we are making forward- looking statements. Although we believe that our forward-looking statements are based on reasonable assumptions, our expected results may not be achieved, and actual results may differ materially from our expectations. In addition, important factors that could cause actual results to differ from expectations include, among others: (i) our ability or inability to execute our strategic growth plan, including our ability to invest according to plan, grow our businesses (including through joint ventures or other co-investment vehicles), incorporate alternative technologies into our offerings, achieve satisfactory returns on new product offerings, continue our revenue management, expand and manage our global operations, complete acquisitions on satisfactory terms, integrate acquired companies efficiently and transition to more sustainable sources of energy; (ii) changes in customer preferences and demand for our storage and information management services, including as a result of the shift from paper and tape storage to alternative technologies that require less physical space; (iii) the costs of complying with and our ability to comply with laws, regulations and customer requirements, including those relating to data privacy and cybersecurity issues, as well as fire and safety and environmental standards; (iv) the impact of attacks on our internal information technology (“IT”) systems, including the impact of such incidents on our reputation and ability to compete and any litigation or disputes that may arise in connection with such incidents; (v) our ability to fund capital expenditures; (vi) the impact of our distribution requirements on our ability to execute our business plan; (vii) our ability to remain qualified for taxation as a real estate investment trust for United States federal income tax purposes (“REIT”); (viii) changes in the political and economic environments in the countries in which we operate and changes in the global political climate; (ix) our ability to raise debt or equity capital and changes in the cost of our debt; (x) our ability to comply with our existing debt obligations and restrictions in our debt instruments; (xi) the impact of service interruptions or equipment damage and the cost of power on our data center operations; (xii) the cost or potential liabilities associated with real estate necessary for our business; (xiii) unexpected events, including those resulting from climate change or geopolitical events, could disrupt our operations and adversely affect our reputation and results of operations; (xiv) failures to implement and manage new IT systems; (xv) other trends in competitive or economic conditions affecting our financial condition or results of operations not presently contemplated; and (xvi) the other risks described in our periodic reports filed with the SEC, including under the caption “Risk Factors” in Part I, Item 1A of our Annual Report. Except as required by law, we undertake no obligation to update any forward-looking statements appearing in this Supplemental Financial Information. Acquisition and Integration Costs: We define Acquisition and Integration Costs as 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. Adjusted Earnings Per Share, or Adjusted EPS: We define Adjusted EPS as reported earnings per share fully diluted from net income (loss) attributable to Iron Mountain Incorporated (inclusive of our share of adjusted losses (gains) from our unconsolidated joint ventures) and excluding certain items, specifically: (i) Acquisition and Integration Costs; (ii) Restructuring and other transformation; (iii) Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate); (iv) Other expense (income), net; (v) Stock-based compensation expense; (vi) Non-cash amortization related to derivative instruments; (vii) Tax impact of reconciling items and discrete tax items; and (viii) Amortization related to the write-off of certain customer relationship intangible assets. We do not believe these excluded items to be indicative of our ongoing operating results, and they are not considered when we are forecasting our future results. We believe Adjusted EPS is of value to our current and potential investors when comparing our results from past, present and future periods. Non-Cash Amortization of Derivative Instruments: Includes amortization on instruments such as cross-currency swap agreements designated as a hedge of net investment. Adjusted EBITDA and Adjusted EBITDA Margin: We define Adjusted EBITDA as net income (loss) before interest expense, net, provision (benefit) for income taxes, depreciation and amortization (inclusive of our share of Adjusted EBITDA from our unconsolidated joint ventures), and excluding certain items we do not believe to be indicative of our core operating results, specifically: (i) Acquisition and Integration Costs; (ii) Restructuring and other transformation; (iii) Loss (gain) on disposal/write-down of property, plant and equipment, net (including real estate); (iv) Other expense (income), net; (v) Stock-based compensation expense; and (vi) Intangible impairments. Adjusted EBITDA Margin is calculated by dividing Adjusted EBITDA by total revenues. We use multiples of current or projected Adjusted EBITDA in conjunction with our discounted cash flow models to determine our estimated overall enterprise valuation and to evaluate acquisition targets. We believe Adjusted EBITDA and Adjusted EBITDA Margin provide our current and potential investors with relevant and useful information regarding our ability to generate cash flows to support business investment. These measures are an integral part of the internal reporting system we use to assess and evaluate the operating performance of our business. Funds From Operations, FFO (Nareit), and FFO (Normalized): Funds from operations ("FFO") is defined by the National Association of Real Estate Investment Trusts as net income (loss) excluding depreciation on real estate assets, losses and gains on sale of real estate, net of tax, and amortization of data center leased-based intangibles (“FFO (Nareit)”). We calculate our FFO measures, including FFO (Nareit), adjusting for our share of reconciling items from our unconsolidated joint ventures. FFO (Nareit) does not give effect to real estate depreciation because these amounts are computed, under GAAP, to allocate the Section X - Appendix and Definitions investors.ironmountain.com Q1 2025 Supplemental Financial Information 22

cost of a property over its useful life. Because values for well-maintained real estate assets have historically increased or decreased based upon prevailing market conditions, we believe that FFO (Nareit) provides investors with a clearer view of our operating performance. Our most directly comparable GAAP measure to FFO (Nareit) is net income (loss). We modify FFO (Nareit), as is common among REITs seeking to provide financial measures that most meaningfully reflect their particular business ("FFO (Normalized)"). Our definition of FFO (Normalized) excludes certain items included in FFO (Nareit) that we believe are not indicative of our core operating results, specifically: (i) Acquisition and Integration Costs; (ii) Restructuring and other transformation; (iii) Loss (gain) on disposal/write-down of property, plant and equipment, net (excluding real estate); (iv) Other expense (income), net; (v) Stock-based compensation expense; (vi) Non-cash amortization related to derivative instruments; (vii) Real estate financing lease depreciation; (viii) Tax impact of reconciling items and discrete tax items; (ix) Intangible impairments; and (x) (Income) loss from discontinued operations, net of tax. FFO (Normalized) per share: FFO (Normalized) divided by weighted-average fully-diluted shares outstanding. Adjusted Funds From Operations, or AFFO: We define adjusted funds from operations or AFFO as FFO (Normalized) (1) excluding (i) non-cash rent expense (income); (ii) depreciation on non-real estate assets; (iii) amortization expense associated with customer and supplier relationship value, intake costs, acquisition of customer and supplier relationships, capitalized commissions and other intangibles; (iv) amortization of deferred financing costs and debt discount/ premium; (v) revenue reduction associated with amortization of customer inducements and above- and below-market data center leases; and (vi) the impact of reconciling to normalized cash taxes; and (2) including recurring capital expenditures. We also adjust for these items to the extent attributable to our portion of unconsolidated ventures. We believe that AFFO, as a widely recognized measure of operations of REITs, is helpful to investors as a meaningful supplemental comparative performance measure to other REITs, including on a per share basis. AFFO should be considered in addition to, but not as a substitute for, other measures of financial performance reported in accordance with GAAP, such as operating income, net income (loss) or cash flows from operating activities (as determined in accordance with GAAP). AFFO per share: Calculated as AFFO divided by weighted-average fully-diluted shares outstanding. Terminations/Permanent Withdrawal Fees: Revenue from the preparation, documentation, and permanent withdrawal of records. Business Segments: The Global Records and Information Management ("Global RIM"): Records Management, stores physical records and provides information services, vital records services, courier operations, and the collection, handling and disposal of sensitive documents ("Records Management") for customers in 60 countries around the globe. Data Management, provides storage and rotation of backup computer media as part of corporate disaster recovery plans, including service and courier operations, server and computer backup services and related services offerings ("Data Management"). Global Digital Solutions, develops, implements and supports comprehensive storage and information management solutions for the complete lifecycle of our customers’ information, including the management of physical records, conversion of documents to digital formats and digital storage of information ("Global Digital Solutions"). Secure Shredding, includes the scheduled pick-up of office records that customers accumulate in specially designed secure containers we provide and is a natural extension of our hardcopy records management operations, completing the lifecycle of a record. Through a combination of shredding facilities and mobile shredding units consisting of custom built trucks, we are able to offer secure shredding services to our customers. Entertainment Services, entertainment and media services which help industry clients store, safeguard and deliver physical media of all types, and provides digital content repository systems that house, distribute, and archive key media assets ("Entertainment Services"). Consumer Storage, provides on-demand, valet storage for consumers ("Consumer Storage") utilizing data analytics and machine learning to provide effective customer acquisition and a convenient and seamless consumer storage experience. Global Data Center Business: Provides enterprise-class data center facilities and hyperscale-ready capacity to protect mission-critical assets and ensure the continued operation of our customers’ IT infrastructure, with secure, reliable and flexible data center options. Corporate and Other: Consists primarily of our Fine Arts and asset lifecycle management ("ALM") businesses and other corporate items (Corporate and Other). Our Fine Arts business provides technical expertise in the handling, installation and storing of art. Our ALM business provides hyperscale and corporate IT infrastructure managers with services and solutions that enable the decommissioning, data erasure processing and disposition or sale of IT hardware and component assets. ALM services are enabled by: secure logistics, chain of custody and complete asset traceability practices, environmentally-responsible asset processing and recycling, and data sanitization and asset refurbishment services that enable value recovery through asset remarketing. In addition, ALM also offers workplace IT asset management services including storage, configuration, deployment, device support and end-of-life disposition for employee IT devices. Our ALM service focus on protecting and eradicating customer data while maintaining strong, auditable, and transparent chain of custody practices. Corporate and Other includes costs related to executive and staff functions, including finance, human resources and IT, which benefit the enterprise as a whole. Section X - Appendix and Definitions investors.ironmountain.com Q1 2025 Supplemental Financial Information 23

Capital Expenditures and Investments: Our business requires capital expenditures to support our expected storage rental revenue and service revenue growth and ongoing operations, new products and services and increased profitability. The majority of our capital goes to support business line growth and our ongoing operations. Additionally, we invest capital to acquire or construct real estate. We also expend capital to support the development and improvement of products and services and projects designed to increase our profitability. These expenditures are generally discretionary in nature. We categorize our capital expenditures as follows: Growth Investment: Data Center - Expenditures primarily related to investments in the construction of data center facilities (including the acquisition of land), as well as investments to drive revenue growth, expand capacity or achieve operational or cost efficiencies. Real Estate - Expenditures primarily related to investments in land, buildings, building improvements, leasehold improvements and racking structures to grow our revenues, extend the useful life of an asset or achieve operational or cost efficiencies. Innovation and Other - Discretionary capital expenditures for significant new products and services as well as computer hardware and software to support new products and services or to achieve operational or cost efficiencies. Integration costs of acquisitions are also included. Recurring: Data Center - Expenditures related to the replacement of equivalent components and overall maintenance of existing data center assets. Real Estate - Expenditures primarily related to the replacement of components of real estate assets such as buildings, building improvements, leasehold improvements and racking structures. Non-Real Estate - Expenditures primarily related to the replacement of containers and shred bins, warehouse equipment, fixtures, computer hardware, or third-party or internally-developed software assets that support the maintenance of existing revenues or avoidance of an increase in costs. Constant Currency: Adjusts results to normalize Fx impacts across comparable periods. Data Center Business Definitions: Leaseable MW - Represents the amount of critical power capacity available for customer use, measured in megawatts (MW). Monthly Recurring Revenue (MRR) - Defined as recurring contractual revenue under existing commenced customer leases, including rent, power, and other recurring data center services. Pre-leased - A lease on data center capacity that is signed before construction has completed. Pre-Stabilized - A building recently placed in service which has not yet reached 85% leased or 24 months in service. Rental Churn Rate - Represents data center leases which are not renewed or are terminated during the period. Rental churn is calculated based on the MRR terminated in the period, compared with total MRR at the beginning of the period. TCV - “Total Contract Value” represents total revenue contracted for active contracts through the contract term, not including renewals or extensions, but including fixed power charges. Total potential MW - Total amount of existing and planned critical power capacity at full build-out, measured in megawatts. WALE - “Weighted Average Lease Expiry” (in years) is calculated on a revenue basis, using annual GAAP revenue of all in-place contracts, excluding utility reimbursements. EBITDAR: Calculated using a trailing four fiscal quarter basis earnings before interest, taxes, depreciation and amortization and rent expense (“EBITDAR”) of our consolidated subsidiaries, other than those we have designated as “Unrestricted Subsidiaries” as defined in our Credit Agreement, subject to certain adjustments and exclusions, which make the calculation of financial performance for purposes of EBITDAR calculations not directly comparable to our presentation of Adjusted EBITDA. Credit Facility Fixed Charge Coverage Ratio: Calculated using a trailing four fiscal quarter basis EBITDAR divided by scheduled amortization, interest expense related to outstanding debt and preferred equity, if any, and rent expenses of our consolidated subsidiaries, other than those we have designated as “Unrestricted Subsidiaries” as defined in our Credit Agreement. Net Lease-Adjusted Leverage Ratio: Calculated as net debt, including the capitalized value of lease obligations, of our consolidated subsidiaries, other than those we have designated as “Unrestricted Subsidiaries” as defined in our Credit Agreement, plus six times rent expenses divided by EBITDAR. Organic Revenue Growth: Our organic revenue growth rate, represents the year-over-year growth rate of our revenues excluding the impact of business acquisitions, divestitures and foreign currency exchange rate fluctuations. Our organic revenue growth rates includes the impact of acquisitions of customer relationships. Records Management Retention Rate: Calculated as one minus the result of dividing the total number of cubic feet of records removed from inventory due to customer terminations and destructions in a one-year period by the total number of cubic feet of records in storage at the beginning of the period. Storage Rev/NOI per Sq. Ft.: Calculated as either storage revenue or Storage NOI (as defined below) divided by the quarterly building square foot average for storage products. Section X - Appendix and Definitions investors.ironmountain.com Q1 2025 Supplemental Financial Information 24

Service Profit and Margin: The Gross Profit and Margin attributable to the global service business. Calculated as follows: Total Revenues from Adjusted Service Activities - Service Cost of Sales = Service Gross Profit ($) / Total Revenues from Adjusted Service Activities = Service Gross Margin (%) Storage Net Operating Income, or Storage NOI: Storage NOI is defined as revenue from rental activities (storage rental revenue, termination fees and permanent withdrawal fees) less storage rental costs. Storage rental costs include facility costs (excluding rent), storage rental labor, other storage costs and allocated overhead. Storage NOI is commonly used in the REIT industry and enables investors to understand and value the income generated from the company’s real estate. Storage Profit and Margin: Gross Profit and Margin attributable to the global storage business. Calculated as follows: Total Revenue from Adjusted Storage Rental Activities - Storage Rental Cost of Sales = Storage Rental Gross Profit ($) / Total Revenue from Adjusted Storage Rental Activities = Storage Rental Gross Margin (%) Tax Rates: Effective Tax Rate - GAAP tax rate for the period calculated as tax expense or benefit for the quarter (total of current and deferred tax provisions), including discrete items, and divided by profit before tax for the period. Structural Tax Rate - Estimated tax rate for the full fiscal year calculated based on forecasted ordinary income and forecasted tax expense/benefit excluding any significant unusual or infrequently occurring items (i.e., discrete items) and items recognized net of tax on the financials (i.e., discontinued operations). Total Storage Volume: Iron Mountain’s comprehensive portfolio of physical storage, including Global RIM and Corporate and Other, calculated on an absolute basis in cubic feet. Section X - Appendix and Definitions investors.ironmountain.com Q1 2025 Supplemental Financial Information 25