Supplemental Financial Information Fourth Quarter 2021 investors.ironmountain.com

Table of Contents Section I - Q4 Earnings Press Release 3 Q4 2021 Earnings Press Release Section II - Company Profile 6 Section III - Financial Highlights Financial and Operating Highlights 7 Organic Revenue Growth 8 Section IV - Operational Metrics Worldwide Storage Volume 9 Quarterly Operating Performance 10 Full Year Operating Performance 11 Section V - Balance Sheets, Statements of Operations and Reconciliations Consolidated Balance Sheets 12 Consolidated Statements of Operations 13 Consolidated Statements of Operations Full Year 14 Reconciliation of Net Income (Loss) to Adjusted EBITDA 15 Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share 16 Reconciliation of Net Income (Loss) to FFO and AFFO 17 Reconciliation of Net Income (Loss) to FFO and AFFO Full Year 19 Section VI - Storage and Service Reconciliation Storage and Service Business Detail 21 Storage and Service Business Detail Full Year 22 Section VII - Real Estate Metrics 23 Global Real Estate Portfolio and Lease Obligations Facility Lease Expirations Section VIII - Data Center Customer and Portfolio Metrics Data Center Customer Lease Expiration and Leasing Activity Summary 24 Data Center Operating Portfolio 25 Data Center Expansion and Development Activity 26 Section IX - Capitalization and Debt Maturity Profile 27 Capitalization Debt Maturity Profile Section X - Capital Expenditures and Acquisitions Capital Expenditures and Investments 28 Business and Customer Acquisitions 29 Section XI - Appendix and Definitions 31 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 December 31, 2021 unless noted Unaudited investors.ironmountain.com Q4 2021 Supplemental Financial Information 2

Iron Mountain Reports Fourth Quarter and Full Year 2021 Results -- Full Year Net Income increases 32%; Achieves record quarterly and annual Revenue, AFFO and Adjusted EBITDA -- -- Issues Full Year 2022 Guidance; Growth at midpoint of 16% Revenue and 12% Adjusted EBITDA -- BOSTON – February 24, 2022 – Iron Mountain Incorporated (NYSE: IRM), a global leader in innovative storage, data center infrastructure, asset lifecycle management and information management services, announces record financial and operating results for the fourth quarter and full year 2021. The conference call / webcast details, earnings call 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. Reconciliations of non-GAAP measures to the appropriate GAAP measures are included herein. “We are pleased to have delivered exceptional performance in the fourth quarter, marking a record year both in terms of revenue and profitability - in spite of COVID still impacting some of our traditional services. This record result is reflective of our expanding and broad offerings, continued resiliency in our storage businesses, deep customer relationships, and strength of our team," said William L. Meaney, President and CEO of Iron Mountain. "Despite the challenges associated with the pandemic, our Mountaineers around the world have continued to put our customers first. This customer-first mindset has delivered accelerated growth for our company as a result of solving more and more of our customers' critical issues linked to their digital transformation and asset protection initiatives. As we look ahead, we have never been more confident in our ability to continue to create meaningful value for our customers and our shareholders." Financial Performance Highlights for the Fourth Quarter and Full Year 2021 ($ in millions, except per share data) Three Months Ended Full Year Ended 12/31/21 12/31/20 Y/Y % Change 12/31/21 12/31/20 Y/Y % Change Storage Rental Revenue $725 $697 4% $2,870 $2,754 4% Service Revenue $434 $362 20% $1,621 $1,393 16% Total Revenue $1,160 $1,060 9% $4,492 $4,147 8% Net Income (Loss) $61 $247 (75)% $453 $343 32% Adjusted EBITDA $431 $374 15% $1,635 $1,476 11% Adjusted EBITDA Margin 37.1% 35.3% +180 bps 36.4% 35.6% +80 bps AFFO $267 $191 40% $1,012 $888 14% AFFO per share $0.92 $0.66 39% $3.48 $3.07 13% • Total reported Revenues for the fourth quarter were $1.16 billion, compared with $1.06 billion in the fourth quarter of 2020, an increase of 9.4%. Excluding the impact of foreign currency exchange (FX), total reported Revenues increased 9.9% compared to the prior year, driven by a 20.4% increase in Service revenue, while Storage rental revenue increased 4.5%. For the full year, total reported Revenues increased 8.3%, or 6.8%, excluding the impact of FX. • Net Income for the fourth quarter was $61.5 million compared with $246.8 million in the fourth quarter of 2020. The following items were included in Net Income: ◦ Restructuring Charges of $76.7 million associated with the implementation of Project Summit in the fourth quarter of 2021 compared to $65.7 million in the fourth quarter of 2020. ◦ Gain on Disposal/Write-Down of PP&E, Net of $37.7 million in the fourth quarter of 2021 compared to $285.4 million in the fourth quarter of 2020, primarily related to the company's capital recycling program. • For the full year, Net Income was $452.7 million, compared with $343.1 million in 2020. The following items were included in the full year ended 2021 and 2020, respectively: ◦ Restructuring Charges of $206.4 million compared to $194.4 million. ◦ Intangible Impairment charge of $23.0 million related to the writedown of goodwill associated with the Fine Arts business in the first quarter of 2020. ◦ Gain on Disposal/Write-Down of PP&E, Net of $172.0 million compared to $363.5 million, primarily related to the company's capital recycling program. ◦ Other Income, Net of $192.8 million, primarily related to a gain on sale from the divestment of the company's Intellectual Property Management business, compared to Other Expense, Net of $143.5 million, primarily related to a debt extinguishment charge and foreign currency translation losses. Section I - Q4 Earnings Press Release investors.ironmountain.com Q4 2021 Supplemental Financial Information 3

• Adjusted EBITDA for the fourth quarter was $430.7 million, compared with $374.2 million in the fourth quarter of 2020, an increase of 15.1%. On a constant currency basis, Adjusted EBITDA increased by 15.4%, driven by the strong increase in Service revenue and benefits from Project Summit. For the full year, Adjusted EBITDA was $1.635 billion, compared with $1.476 billion in full year 2020, an increase of 10.8%. On a constant currency basis, Adjusted EBITDA increased 9.1%. • Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated for the fourth quarter was $0.21, compared with $0.86 in the fourth quarter of 2020. For the full year, Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated was $1.55, compared with $1.19 in full year 2020. • Adjusted EPS for the fourth quarter was $0.43, compared with $0.29 in the fourth quarter of 2020. Adjusted EPS reflects a structural tax rate of 17.7% and 15.1%, in the fourth quarters of 2021 and 2020, respectively. For the full year, Adjusted EPS was $1.51, compared with $1.19 in full year 2020. • FFO (Normalized) per share was $0.74 for the fourth quarter, compared with $0.60 in the fourth quarter of 2020, an increase of 23.3%. For the full year, FFO (Normalized) per share was $2.76, compared with $2.42 in full year 2020, an increase of 14.0%. • AFFO was $267.0 million for the fourth quarter, compared with $190.8 million in the fourth quarter of 2020, an increase of 40.0%, driven by improved EBITDA in 2021 and higher levels of recurring capital spend in the fourth quarter of 2020 as the Company caught up on delayed activities due to the pandemic. For the full year, AFFO was $1.012 billion, compared with $887.5 million in full year 2020, an increase of 14.0%. • AFFO per share was $0.92 for the fourth quarter, compared with $0.66 in the fourth quarter of 2020, an increase of 38.7%, driven by improved EBITDA in 2021 and higher levels of recurring capital spend in the fourth quarter of 2020 as the Company caught up on delayed activities due to the pandemic. For the full year, AFFO per share was $3.48, compared with $3.07 in full year 2020, an increase of 13.4%. • Global RIM business revenue increased 8.1% in the fourth quarter, or an 8.6% increase compared to the fourth quarter of 2020, excluding the impact of FX. For the full year, total revenue increased 7.5%, or 5.9%, excluding the impact of FX. Global RIM Adjusted EBITDA margin increased 160 basis points in the fourth quarter and 100 basis points for the full year as compared to 2020. Improved profitability was driven by revenue management, productivity and record volume levels. • Global Data Center business revenue increased 24.7% in the fourth quarter, or a 25.3% increase compared to the fourth quarter of 2020, excluding the impact of FX. For the full year, total revenue increased 17.0%, or 16.2%, excluding the impact of FX. Iron Mountain executed 27 megawatts of new and expansion leases in the fourth quarter, bringing total new and expansion leasing activity to 49 megawatts for the full year 2021. Dividend On February 24, 2022, Iron Mountain's Board of Directors declared a quarterly cash dividend of $0.6185 per share for the first quarter. The first- quarter 2022 dividend is payable on April 6, 2022, for shareholders of record on March 15, 2022. Guidance Iron Mountain issued full year 2022 guidance inclusive of closed transactions; details are summarized in the table below. 2022 Guidance(1) ($ in millions, except per share data) 2022 Guidance Y/Y % Change Total Revenue $5,125 - $5,275 14% - 17% Adjusted EBITDA $1,800 - $1,850 10% - 13% AFFO $1,085 - $1,120 7% - 11% AFFO Per Share $3.70 - $3.82 6% - 10% (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. About Iron Mountain Iron Mountain Incorporated (NYSE: IRM) is a global leader in innovative storage, asset lifecycle management and information management services. Founded in 1951 and trusted by more than 225,000 customers worldwide, Iron Mountain helps customers CLIMB HIGHER™ to transform their businesses. Through a range of services including digital transformation, data centers, secure records storage, information management, asset lifecycle management, secure destruction, and art storage and logistics, Iron Mountain helps businesses bring light to their dark data, enabling customers to unlock value and intelligence from their stored digital and physical assets at speed and with security, while helping them meet their environmental goals. To learn more about Iron Mountain, please visit: www.IronMountain.com and follow @IronMountain on Twitter and LinkedIn. Section I - Q4 Earnings Press Release investors.ironmountain.com Q4 2021 Supplemental Financial Information 4

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: We have made statements in this Annual Report 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 operations, economic performance, financial condition, goals, beliefs, future growth strategies, investment objectives, plans and current expectations, such as our (1) expectations and assumptions regarding the impact of the COVID-19 (as defined below) pandemic on us and our customers, including on our businesses, financial position, results of operations and cash flows, (2) commitment to future dividend payments, (3) expected change in volume of records stored with us, (4) expected growth in revenue, organic revenue, including 2022 consolidated organic storage rental revenue growth rate and consolidated organic total revenue growth rate, and Adjusted EBITDA (as defined below), (5) expectations that profits will increase in our growth portfolio, including our higher-growth markets, (6) expectations related to our revenue management programs and continuous improvement initiatives, (7) expectations related to monetizing our owned industrial real estate assets as part of our capital recycling program, (8) expected ability to identify and complete acquisitions and drive returns on invested capital, (9) anticipated capital expenditures, (10) expected benefits related to Project Summit (as defined below), and (11) other forward-looking statements related to our business, results of operations and financial condition. 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" 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) the severity and duration of the COVID-19 pandemic and its effects on the global economy, including its effects on us, the markets we serve and our customers and the third parties with whom we do business within those markets; (ii) our ability to remain qualified for taxation as a real estate investment trust for United States federal income tax purposes (“REIT”); (iii) 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; (iv) our ability or inability to execute our strategic growth plan, including our ability to invest according to plan, incorporate new digital information technologies into our offerings, achieve satisfactory returns on new product offerings, continue our revenue management, expand internationally, complete acquisitions on satisfactory terms, integrate acquired companies efficiently and grow our business through joint ventures; (v) changes in the amount of our capital expenditures; (vi) our ability to raise debt or equity capital and changes in the cost of our debt; (vii) the cost and our ability to comply with laws, regulations and customer demands, including those relating to data security and privacy issues, as well as fire and safety and environmental standards; (viii) the impact of litigation or disputes that may arise in connection with incidents in which we fail to protect our customers’ information or our internal records or information technology (“IT”) systems and the impact of such incidents on our reputation and ability to compete; (ix) changes in the price for our storage and information management services relative to the cost of providing such storage and information management services; (x) changes in the political and economic environments in the countries in which our international subsidiaries operate and changes in the global political climate, particularly as we consolidate operations and move records and data across borders; (xi) our ability to comply with our existing debt obligations and restrictions in our debt instruments; (xii) the impact of service interruptions or equipment damage and the cost of power on our data center operations; (xiii) the cost or potential liabilities associated with real estate necessary for our business; (xiv) failures in our adoption of new IT systems; (xv) unexpected events, including those resulting from climate change, could disrupt our operations and adversely affect our reputation and results of operations; (xvi) other trends in competitive or economic conditions affecting our financial condition or results of operations not presently contemplated; and (xvii) the other risks described in our periodic reports filed with the SEC, including under the caption "Risk Factors" in Part I, Item 1A of this Annual Report. Except as required by law, we undertake no obligation to update any forward-looking statements appearing in this report. Reconciliation of Non-GAAP Measures: Throughout this release, Iron Mountain discusses (1) Adjusted EBITDA, (2) Adjusted Earnings per Share (“Adjusted EPS”), (3) Funds from Operations (“FFO Nareit”), (4) FFO (Normalized), and (5) Adjusted Funds from Operations (“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. Investor Relations Contacts: Gillian Tiltman Sarah Barry SVP, Head of Investor Relations Manager, Investor Relations gillian.tiltman@ironmountain.com sarah.barry@ironmountain.com (617) 286-4881 (617) 237-6597 Section I - Q4 Earnings Press Release investors.ironmountain.com Q4 2021 Supplemental Financial Information 5

Facts and Figures $4.5 Billion Full Year 2021 Revenue 225,000+ Customer Accounts ~25,000 Employees ~1,450 Facilities Worldwide 89 million+ Pieces of Media 740+ million Cubic Feet of Global Storage Volume Fourth Quarter Revenue and Gross Profit Mix Geographic Revenue Mix 66% 20% 5% 9% North America Europe Latin America Asia Business Revenue Mix 63% 37% Storage Rental Service Business Adjusted Gross Profit Mix 77% 23% Storage Rental Service Product Revenue Mix 62% 10% 7% 4% 7% 9% 1% Records Management Data Management Data Center Adjacent Businesses Global Digital Solutions Secure Shred Consumer Storage RM Revenue by Vertical - Customer Mix North America 16% 2% 8% 12% 6% 3% 3% 1% 50% Healthcare Federal Legal Financial Insurance Life Sciences Energy Business Services Other Section II - Company Profile investors.ironmountain.com Q4 2021 Supplemental Financial Information 6

Financial Highlights Q4 2021 Q3 2021 Q2 2021 Q1 2021 Q4 2020 Storage Rental Revenue $725,177 $718,614 $718,272 $708,056 $697,294 Service Revenue $434,410 $411,534 $401,484 $373,984 $362,359 Total Revenues $1,159,587 $1,130,148 $1,119,756 $1,082,040 $1,059,653 Adjusted EBITDA $430,734 $417,769 $405,631 $380,565 $374,247 Adjusted EBITDA Margin 37.1 % 37.0 % 36.2 % 35.2 % 35.3 % Net Income (Loss) Attributable to Iron Mountain Incorporated $61,648 $67,683 $275,285 $45,603 $247,411 Reported EPS - Fully Diluted $0.21 $0.23 $0.95 $0.16 $0.86 Adjusted EPS $0.43 $0.40 $0.38 $0.32 $0.29 FFO (Normalized) $216,757 $208,836 $199,963 $181,338 $173,483 FFO (Normalized) per Share $0.74 $0.72 $0.69 $0.63 $0.60 AFFO $267,032 $263,484 $245,992 $235,391 $190,771 AFFO per Share $0.92 $0.90 $0.85 $0.81 $0.66 Dividend per Share $0.62 $0.62 $0.62 $0.62 $0.62 TTM AFFO Payout Ratio 71.2 % 76.8 % 80.7 % 80.1 % 80.4 % Weighted Average Common Shares Outstanding - Diluted 291,811 291,482 291,079 289,528 289,161 Net Lease-Adjusted Leverage Ratio 5.3x 5.4x 5.3x 5.5x 5.3x Operating Highlights Q4 2021 Q3 2021 Q2 2021 Q1 2021 Q4 2020 Organic Storage Rental Revenue Growth 3.6 % 2.3 % 2.5 % 1.7 % 1.7 % Organic Service Revenue Growth 17.6 % 17.7 % 25.5 % (4.8) % (12.1) % Total Volume - Storage 743,886 744,280 733,086 728,616 726,430 Storage Facility Capacity Utilization 80.9 % 81.8 % 84.0 % 82.3 % 81.9 % Records Management Retention Rate 94.1 % 94.4 % 94.4 % 94.4 % 93.7 % Storage Revenue / Sq. Ft $7.86 $7.83 $7.93 $7.88 $7.78 Storage NOI / Sq. Ft $6.45 $6.39 $6.43 $6.33 $6.16 Data Center: Leasable Megawatts 176.4 156.6 144.7 136.4 129.8 Leased % - Stabilized 91.2 % 89.4 % 88.4 % 88.5 % 89.0 % Leased % - Total 89.3 % 85.0 % 83.0 % 85.2 % 87.4 % Kilowatts Leased - New/Expansion 27,199 8,989 3,610 9,035 7,435 Churn 0.8 % 3.9 % 1.9 % 2.3 % 3.9 % Number of Facilities 19 19 15 15 15 Number of Markets 16 16 13 13 13 Section III - Financial Highlights investors.ironmountain.com Q4 2021 Supplemental Financial Information 7

Organic Revenue Growth (1) Q4 2021 Q3 2021 Full Year 2021 Reported Constant Currency Organic Revenue Reported Constant Currency Organic Revenue Reported Constant Currency Organic Revenue Storage Rental 4.0% 4.5% 3.6% 3.2% 2.2% 2.3% 4.2% 2.8% 2.6% Service 19.9% 20.4% 17.6% 20.9% 19.7% 17.7% 16.4% 14.7% 13.2% Total Revenues 9.4% 9.9% 8.5% 9.0% 7.9% 7.4% 8.3% 6.8% 6.1% Total Organic Revenue Growth 1.0% (7.2)% (3.4)% (3.4)% (0.6)% 9.7% 7.4% 8.5% Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 (8.0)% (4.0)% 0.0% 4.0% 8.0% 12.0% Organic Storage Rental Revenue Growth 3.0% 2.3% 2.5% 1.7% 1.7% 2.5% 2.3% 3.6% Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 0.0% 2.0% 4.0% 6.0% Organic Service Revenue Growth (2.3)% (23.1)% (13.5)% (12.1)% (4.8)% 25.5% 17.7% 17.6% Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 (30.0)% (20.0)% (10.0)% 0.0% 10.0% 20.0% 30.0% (1) Constant Currency and excluding impact from business acquisitions and divestitures. Section III - Financial Highlights investors.ironmountain.com Q4 2021 Supplemental Financial Information 8

Worldwide Storage Volume Records and Information Management Adjacent Businesses Consumer and Other Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 640,000 660,000 680,000 700,000 720,000 740,000 760,000 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 Records and Information Management 712,388 712,009 711,148 708,981 708,587 710,790 720,069 718,510 Adjacent Businesses 5,938 5,906 6,534 7,077 7,335 7,683 7,961 7,934 Consumer and Other 4,308 6,495 8,967 10,373 12,694 14,613 16,250 17,442 Total 722,634 724,411 726,649 726,430 728,616 733,086 744,280 743,886 Business acquisitions during the quarter (1) 18,389 3,555 272 — — 5,020 10,743 — (1) Business acquisitions volume acquired during the quarter included in total volume. Section IV - Operational Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 9

Fourth Quarter 2021 Y/Y % Change Q4 2021 Q3 2021 Q4 2020 Reported Constant Currency Organic Growth (1) Global RIM Business Storage Rental $622,507 $621,615 $600,419 3.7% 4.2% 2.5% Service 397,853 373,962 343,568 15.8% 16.2% 14.7% Total Revenues $1,020,360 $995,577 $943,987 8.1% 8.6% 6.9% Adjusted EBITDA $452,559 $442,798 $404,398 Adjusted EBITDA Margin 44.4 % 44.5 % 42.8 % Global Data Center Business Storage Rental $78,787 $72,411 $66,872 17.8% 18.6% 14.6% Service 11,439 16,176 5,501 107.9% 116.8% 116.8% Total Revenues $90,226 $88,587 $72,373 24.7% 25.3% 22.4% Adjusted EBITDA $38,388 $35,097 $31,764 Adjusted EBITDA Margin 42.5 % 39.6 % 43.9 % Corporate and Other Business Storage Rental $23,884 $24,587 $30,003 (20.4)% (20.5)% 2.3% Service 25,118 21,397 13,290 89.0% 91.3% 52.5% Total Revenues $49,001 $45,984 $43,293 13.2% 13.5% 21.3% Adjusted EBITDA $(60,213) $(60,126) $(61,916) Total Consolidated Storage Rental $725,177 $718,614 $697,294 4.0% 4.5% 3.6% Service $434,410 411,534 362,359 19.9% 20.4% 17.6% Total Revenues $1,159,587 $1,130,148 $1,059,653 9.4% 9.9% 8.5% Adjusted EBITDA $430,734 $417,769 $374,247 Adjusted EBITDA Margin 37.1 % 37.0 % 35.3 % (1) Constant Currency and excluding impact from business acquisitions and divestitures. Section IV - Operational Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 10

Full Year 2021 Y/Y % Change Full Year 2021 Full Year 2020 Reported Constant Currency Organic Growth (1) Global RIM Business Storage Rental $2,471,894 $2,373,783 4.1% 2.6% 1.9% Service 1,504,269 1,325,497 13.5% 11.8% 11.2% Total Revenues $3,976,163 $3,699,280 7.5% 5.9% 5.2% Adjusted EBITDA $1,734,227 $1,574,069 Adjusted EBITDA Margin 43.6 % 42.6 % Global Data Center Business Storage Rental $289,592 $263,695 9.8% 9.0% 8.0% Service 37,306 15,617 138.9% 137.7% 137.7% Total Revenues $326,898 $279,312 17.0% 16.2% 15.5% Adjusted EBITDA $137,349 $126,576 Adjusted EBITDA Margin 42.0 % 45.3 % Corporate and Other Business Storage Rental $108,633 $116,613 (6.8)% (7.5)% 4.8% Service 79,837 52,065 53.3% 50.5% 24.6% Total Revenues $188,470 $168,678 11.7% 10.5% 11.7% Adjusted EBITDA $(236,877) $(224,924) Total Consolidated Storage Rental $2,870,119 $2,754,091 4.2% 2.8% 2.6% Service 1,621,412 1,393,179 16.4% 14.7% 13.2% Total Revenues $4,491,531 $4,147,270 8.3% 6.8% 6.1% Adjusted EBITDA $1,634,699 $1,475,721 Adjusted EBITDA Margin 36.4 % 35.6 % (1) Constant Currency and excluding impact from business acquisitions and divestitures. Section IV - Operational Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 11

Consolidated Balance Sheets 12/31/2021 12/31/2020 ASSETS Current Assets: Cash and Cash Equivalents $255,828 $205,063 Accounts Receivable, Net 961,419 859,344 Prepaid Expenses and Other 224,020 205,380 Total Current Assets $1,441,267 $1,269,787 Property, Plant and Equipment: Property, Plant and Equipment $8,647,303 $8,246,337 Less: Accumulated Depreciation (3,979,159) (3,743,894) Property, Plant and Equipment, Net $4,668,144 $4,502,443 Other Assets, Net: Goodwill $4,463,531 $4,557,609 Customer Relationships, Customer Inducements and Data Center Lease-Based Intangibles 1,181,043 1,326,977 Operating Lease Right-of-Use Assets 2,314,422 2,196,502 Other 381,624 295,949 Total Other Assets, Net $8,340,620 $8,377,037 Total Assets $14,450,031 $14,149,267 LIABILITIES AND EQUITY Current Liabilities: Current Portion of Long-term Debt $309,428 $193,759 Accounts Payable 369,145 359,863 Accrued Expenses and Other Current Liabilities 1,032,537 1,146,288 Deferred Revenue 307,470 295,785 Total Current Liabilities $2,018,580 $1,995,695 Long-term Debt, Net of Current Portion 8,962,513 8,509,555 Long-term Operating Lease Liabilities, Net of Current Portion 2,171,472 2,044,598 Other Long-term Liabilities 144,053 204,508 Deferred Income Taxes 223,934 198,377 Redeemable Noncontrolling Interests 72,411 59,805 Total Long-term Liabilities $11,574,383 $11,016,843 Total Liabilities $13,592,963 $13,012,538 Equity Total Equity $857,068 $1,136,729 Total Liabilities and Equity $14,450,031 $14,149,267 Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 12

Quarterly Consolidated Statements of Operations Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Revenues: Storage Rental $725,177 $718,614 0.9 % $697,294 4.0 % Service 434,410 411,534 5.6 % 362,359 19.9 % Total Revenues $1,159,587 $1,130,148 2.6 % $1,059,653 9.4 % Operating Expenses: Cost of Sales (excluding Depreciation and Amortization) $479,078 $481,663 (0.5) % $449,224 6.6 % Selling, General and Administrative 262,461 241,596 8.6 % 236,438 11.0 % Depreciation and Amortization 173,277 174,818 (0.9) % 168,383 2.9 % Acquisition and Integration Costs 9,349 1,138 721.7 % — — Restructuring Charges 76,740 50,432 52.2 % 65,681 16.8 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (37,720) (935) 3,934.2 % (285,366) (86.8) % Total Operating Expenses $963,185 $948,712 1.5 % $634,359 51.8 % Operating Income (Loss) $196,402 $181,436 8.2 % $425,294 (53.8) % Interest Expense, Net 104,510 103,809 0.7 % 105,127 (0.6) % Other Expense (Income), Net 7,214 (18,501) (139.0) % 77,108 (90.6) % Net Income (Loss) Before Provision (Benefit) for Income Taxes $84,678 $96,128 (11.9) % $243,060 (65.2) % Provision (Benefit) for Income Taxes 23,217 28,017 (17.1) % (3,695) (728.3) % Net Income (Loss) $61,461 $68,111 (9.8) % $246,755 (75.1) % Less: Net (Loss) Income Attributable to Noncontrolling Interests (187) 428 (143.7) % (656) (71.5) % Net Income (Loss) Attributable to Iron Mountain Incorporated $61,648 $67,683 (8.9) % $247,411 (75.1) % Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated: Basic $0.21 $0.23 (8.7) % $0.86 (75.6) % Diluted $0.21 $0.23 (8.7) % $0.86 (75.6) % Weighted Average Common Shares Outstanding - Basic 290,064 289,762 0.1 % 288,419 0.6 % Weighted Average Common Shares Outstanding - Diluted 291,811 291,482 0.1 % 289,161 0.9 % Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 13

Full Year Consolidated Statement of Operations Full Year 2021 Full Year 2020 % Change Revenues: Storage Rental $2,870,119 $2,754,091 4.2 % Service 1,621,412 1,393,179 16.4 % Total Revenues $4,491,531 $4,147,270 8.3 % Operating Expenses: Cost of Sales (excluding Depreciation and Amortization) (1) $1,887,229 $1,757,342 7.4 % Selling, General and Administrative (2) 1,022,559 949,215 7.7 % Depreciation and Amortization 680,422 652,069 4.3 % Acquisition and Integration Costs 12,764 — — Restructuring Charges 206,426 194,396 6.2 % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (172,041) (363,537) (52.7) % Total Operating Expenses $3,637,359 $3,212,485 13.2 % Operating Income (Loss) $854,172 $934,785 (8.6) % Interest Expense, Net 417,961 418,535 (0.1) % Other (Income) Expense, Net (192,804) 143,545 (234.3) % Net Income (Loss) Before Provision (Benefit) for Income Taxes $629,015 $372,705 68.8 % Provision (Benefit) for Income Taxes 176,290 29,609 495.4 % Net Income (Loss) $452,725 $343,096 32.0 % Less: Net Income (Loss) Attributable to Noncontrolling Interests 2,506 403 521.8 % Net Income (Loss) Attributable to Iron Mountain Incorporated $450,219 $342,693 31.4 % Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated: Basic $1.56 $1.19 31.1 % Diluted $1.55 $1.19 30.3 % Weighted Average Common Shares Outstanding - Basic 289,457 288,183 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,975 288,643 0.8 % (1) Includes $7.6M of direct and incremental costs related to COVID-19 in Full Year 2020. (2) Includes $1.6M of direct and incremental costs related to COVID-19 in Full Year 2020. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 14

Quarterly Reconciliation of Net Income (Loss) to Adjusted EBITDA Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Net Income (Loss) $61,461 $68,111 (9.8) % $246,755 (75.1) % Add / (Deduct): Interest Expense, Net 104,510 103,809 0.7 % 105,127 (0.6) % Provision (Benefit) for Income Taxes 23,217 28,017 (17.1) % (3,695) (728.3) % Depreciation and Amortization 173,277 174,818 (0.9) % 168,383 2.9 % Acquisition and Integration Costs 9,349 1,138 721.7 % — — Restructuring Charges 76,740 50,432 52.2 % 65,681 16.8 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (37,720) (935) 3,934.2 % (285,366) (86.8) % Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 3,255 (21,517) (115.1) % 74,212 (95.6) % Stock-Based Compensation Expense 15,088 12,644 19.3 % 2,216 580.9 % Our Share of Adjusted EBITDA Reconciling Items from our Unconsolidated Joint Ventures 1,557 1,252 24.4 % 175 789.3 % Adjusted EBITDA $430,734 $417,769 3.1 % $374,247 15.1 % Full Year Reconciliation of Net Income (Loss) to Adjusted EBITDA Full Year 2021 Full Year 2020 % Change Net Income (Loss) $452,725 $343,096 32.0 % Add / (Deduct): Interest Expense, Net 417,961 418,535 (0.1) % Provision (Benefit) for Income Taxes 176,290 29,609 495.4 % Depreciation and Amortization 680,422 652,069 4.3 % Acquisition and Integration Costs 12,764 — — Restructuring Charges 206,426 194,396 6.2 % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (172,041) (363,537) (52.7) % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (205,746) 133,611 (254.0) % Stock-Based Compensation Expense 61,001 34,272 78.0 % COVID-19 Costs (1) — 9,285 (100.0) % Our Share of Adjusted EBITDA Reconciling Items from our Unconsolidated Joint Ventures 4,897 1,385 253.6 % Adjusted EBITDA $1,634,699 $1,475,721 10.8 % (1) Costs that are incremental and directly attributable to the COVID-19 pandemic which are not expected to recur once the pandemic ends ("COVID-19 Costs"). These costs include the purchase of personal protective equipment for our employees and incremental cleaning costs of our facilities, among other direct costs. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 15

Quarterly Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.21 $0.23 (9.0) % $0.86 (75.4) % Add / (Deduct): Acquisition and Integration Costs 0.03 — — — — Restructuring Charges 0.26 0.17 52.0 % 0.23 14.3 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (0.13) — — (0.99) (86.9) % Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 0.01 (0.07) (115.2) % 0.26 (95.7) % Stock-Based Compensation Expense 0.05 0.04 19.2 % 0.01 417.0 % Tax Impact of Reconciling Items and Discrete Tax Items (1) (0.01) 0.02 (167.3) % (0.06) (79.5) % Adjusted EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.43 $0.40 8.0 % $0.29 47.3 % Full Year Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share Full Year 2021 Full Year 2020 % Change Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $1.55 $1.19 30.3 % Add / (Deduct): Acquisition and Integration Costs 0.04 — — Restructuring Charges 0.71 0.67 6.0 % Intangible Impairments — 0.08 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (0.59) (1.26) (53.2) % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (0.71) 0.46 (254.3) % Stock-Based Compensation Expense 0.21 0.12 75.0 % COVID-19 Costs — 0.03 (100.0) % Tax Impact of Reconciling Items and Discrete Tax Items (1) 0.28 (0.11) (354.5) % Income (Loss) Attributable to Noncontrolling Interests 0.01 — — Adjusted EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $1.51 $1.19 26.9 % (1) The difference between our effective tax rates and our structural tax rate (or adjusted effective tax rates) for the quarters and years ended December 31, 2021 and 2020, is primarily due to (i) the reconciling items above, which impact our reported net income (loss) before 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 and years ended December 31, 2021 and 2020 was 17.7% and 15.1%, respectively, and quarter and year to date September 30, 2021 was 16.5%. The Tax Impact of Reconciling Items and Discrete Tax Items is calculated using the current quarter’s estimate of the annual structural tax rate for the full year. This may result in the current period adjustment plus prior reported quarterly adjustments not summing to the full year adjustment. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 16

Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Net Income $61,461 $68,111 (9.8) % $246,755 (75.1) % Add / (Deduct): Real Estate Depreciation (1) 77,423 79,463 (2.6) % 74,618 3.8 % (Gain) Loss on Sale of Real Estate, Net of Tax (36,859) 748 (5,029.5) % (288,248) (87.2) % Data Center Lease-Based Intangible Asset Amortization (2) 10,910 10,458 4.3 % 10,464 4.3 % FFO (Nareit) $112,935 $158,780 (28.9) % $43,589 159.1 % Add / (Deduct): Acquisition and Integration Costs 9,349 1,138 721.7 % — — Restructuring Charges 76,740 50,432 52.2 % 65,681 16.8 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Excluding Real Estate) (861) (1,668) (48.4) % 2,881 (130.2) % Other Expense (Income), Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures 3,255 (21,517) (115.1) % 74,212 (95.6) % Stock-Based Compensation Expense 15,088 12,644 19.3 % 2,216 580.9 % Real Estate Financing Lease Depreciation 3,844 3,740 2.8 % 3,706 3.7 % Tax Impact of Reconciling Items and Discrete Tax Items (3) (3,586) 5,304 (167.6) % (18,795) (80.9) % Our Share of FFO (Normalized) Reconciling Items from our Unconsolidated Joint Ventures (8) (17) (53.0) % (7) 14.3 % FFO (Normalized) $216,757 $208,836 3.8 % $173,483 24.9 % Per Share Amounts (Fully Diluted Shares): FFO (Nareit) $0.39 $0.55 (28.4) % $0.15 160.0 % FFO (Normalized) $0.74 $0.72 2.8 % $0.60 23.3 % Weighted Average Common Shares Outstanding - Basic 290,064 289,762 0.1 % 288,419 0.6 % Weighted Average Common Shares Outstanding - Diluted 291,811 291,482 0.1 % 289,161 0.9 % (1) Includes depreciation expense related to owned real estate assets (land improvements, buildings, building improvements, leasehold of improvements and racking), 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 impact our reported net income (loss) before provision (benefit) for income taxes and (ii) other discrete tax items. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 17

Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO (Continued) Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change FFO (Normalized) $216,757 $208,836 3.8 % $173,483 24.9 % Add / (Deduct): Non-Real Estate Depreciation 36,535 37,128 (1.6) % 34,461 6.0 % Amortization Expense (1) 36,181 36,361 (0.5) % 38,114 (5.1) % Amortization of Deferred Financing Costs 4,078 4,027 1.3 % 4,226 (3.5) % Revenue Reduction Associated with Amortization of Permanent Withdrawal Fees and Above - and Below-Market Leases 2,274 2,251 1.0 % 2,267 0.3 % Non-Cash Rent Expense (Income) 2,165 3,722 (41.8) % 1,896 14.2 % Reconciliation to Normalized Cash Taxes 13,009 8,133 60.0 % (938) (1,486.9) % Our Share of AFFO Reconciling Items from our Unconsolidated Joint Ventures 1,747 1,021 71.2 % 830 1,131.1 % Less: Recurring Capital Expenditures 45,714 37,995 20.3 % 63,567 (28.1) % AFFO $267,032 $263,484 1.3 % $190,771 40.0 % Per Share Amounts (Fully Diluted Shares): AFFO Per Share $0.92 $0.90 1.2 % $0.66 38.7 % Weighted Average Common Shares Outstanding - Basic 290,064 289,762 0.1 % 288,419 0.6 % Weighted Average Common Shares Outstanding - Diluted 291,811 291,482 0.1 % 289,161 0.9 % (1) Includes Customer Relationship Value, intake costs, acquisition of customer relationships, and other intangibles. Excludes amortization of capitalized commissions of $8.4M, $7.7M, and $7.0M in Q4 2021, Q3 2021, and Q4 2020, respectively. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 18

Full Year Reconciliation of Net Income (Loss) to FFO and AFFO Full Year 2021 Full Year 2020 % Change Net Income $452,725 $343,096 32.0 % Add / (Deduct): Real Estate Depreciation (1) 307,717 298,943 2.9 % (Gain) Loss on Sale of Real Estate, Net of Tax (142,892) (365,709) (60.9) % Data Center Lease-Based Intangible Asset Amortization (2) 42,333 42,637 (0.7) % FFO (Nareit) $659,883 $318,967 106.9 % Add / (Deduct): Acquisition and Integration Costs 12,764 — — Restructuring Charges 206,426 194,396 6.2 % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Excluding Real Estate) (3,751) 2,523 (248.7) % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (205,746) 133,611 (254.0) % Stock-Based Compensation Expense 61,001 34,272 78.0 % COVID-19 Costs — 9,285 (100.0) % Real Estate Financing Lease Depreciation 14,635 13,801 6.0 % Tax Impact of Reconciling Items and Discrete Tax Items (3) 56,822 (31,825) (278.5) % Our Share of FFO (Normalized) Reconciling Items from our Unconsolidated Joint Ventures (38) (38) — FFO (Normalized) $801,996 $697,992 14.9 % Per Share Amounts (Fully Diluted Shares): FFO (Nareit) $2.27 $1.11 104.5 % FFO (Normalized) $2.76 $2.42 14.0 % Weighted Average Common Shares Outstanding - Basic 289,457 288,183 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,975 288,643 0.8 % (1) Includes depreciation expense related to owned real estate assets (land improvements, buildings, building improvements, leasehold of improvements and racking), 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 impact our reported net income (loss) before provision (benefit) for income taxes and (ii) other discrete tax items. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 19

Full Year Reconciliation of Net Income (Loss) to FFO and AFFO (Continued) Full Year 2021 Full Year 2020 % Change FFO (Normalized) $801,996 $697,992 14.9 % Add / (Deduct): Non-Real Estate Depreciation 142,720 134,819 5.9 % Amortization Expense (1) 142,278 137,817 3.2 % Amortization of Deferred Financing Costs 16,548 17,376 (4.8) % Revenue Reduction Associated with Amortization of Permanent Withdrawal Fees and Above - and Below-Market Leases 8,852 9,878 (10.4) % Non-Cash Rent Expense (Income) 15,256 10,172 50.0 % Reconciliation to Normalized Cash Taxes 27,801 21,508 29.3 % Our Share of AFFO Reconciling Items from our Unconsolidated Joint Ventures 4,649 1,064 336.9 % Less: Recurring Capital Expenditures 148,201 143,092 3.6 % AFFO $1,011,899 $887,534 14.0 % Per Share Amounts (Fully Diluted Shares): AFFO Per Share $3.48 $3.07 13.4 % Weighted Average Common Shares Outstanding - Basic 289,457 288,183 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,975 288,643 0.8 % (1) Includes Customer Relationship Value, intake costs, acquisition of customer relationships, and other intangibles. Excludes amortization of capitalized commissions of $30.8M and $24.1M in 2021 and 2020, respectively. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q4 2021 Supplemental Financial Information 20

Quarterly Storage Rental and Service Business Detail Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Storage Rental Business Detail Total Storage Rental Revenue $725,177 $718,614 0.9 % $697,294 4.0 % Plus: Terminations/Permanent Withdrawal Fees 7,763 5,612 38.3 % 5,739 35.3 % Total Revenue from Adjusted Storage Rental Activities $732,940 $724,225 1.2 % $703,033 4.3 % Less: Storage Rental Expenses Storage Rent 103,695 104,513 (0.8) % 93,300 11.1 % Other Facility Costs 88,549 87,613 1.1 % 91,733 (3.5) % Storage Rental Labor 5,787 7,120 (18.7) % 6,966 (16.9) % Other Storage Rental Expenses 10,481 8,206 27.7 % 11,151 (6.0) % Storage Rental Cost of Sales $208,512 $207,452 0.5 % $203,150 2.6 % Storage Rental Gross Profit $524,429 $516,773 1.5 % $499,884 4.9 % Storage Rental Gross Margin 71.6 % 71.4 % 20 bps 71.1 % 50 bps Storage Rental Allocated Overhead 35,685 35,026 1.9 % 40,697 (12.3) % Total Storage Rental Adjusted EBITDA $488,743 $481,747 1.5 % $459,186 6.4 % Storage Rent 103,695 104,513 (0.8) % 93,300 11.1 % Storage Rental Net Operating Income $592,438 $586,260 1.1 % $552,486 7.2 % Service Business Detail Total Service Revenue $434,410 $411,534 5.6 % $362,359 19.9 % Less: Terminations/Permanent Withdrawal Fees 7,763 5,612 38.3 % 5,739 35.3 % Total Revenue from Adjusted Service Activities $426,647 $405,922 5.1 % $356,620 19.6 % Less: Service Expenses Service Rent 2,713 2,838 (4.4) % 3,088 (12.1) % Other Facility Costs 7,352 7,508 (2.1) % 6,376 15.3 % Service Labor 185,065 183,165 1.0 % 178,677 3.6 % Other Service Expenses 75,437 80,699 (6.5) % 57,932 30.2 % Service Cost of Sales $270,567 $274,211 (1.3) % $246,072 10.0 % Service Gross Profit $156,080 $131,712 18.5 % $110,548 41.2 % Service Gross Margin 36.6 % 32.4 % 420 bps 31.0 % 560 bps Service Allocated Overhead 23,669 23,900 (1.0) % 25,012 (5.4) % Total Service Adjusted EBITDA $132,411 $107,812 22.8 % $85,534 54.8 % Section VI - Storage and Service Reconciliation investors.ironmountain.com Q4 2021 Supplemental Financial Information 21

Full Year Storage Rental And Service Business Detail Full Year 2021 Full Year 2020 % Change Storage Rental Business Detail Total Storage Rental Revenue $2,870,119 $2,754,091 4.2 % Plus: Terminations/Permanent Withdrawal Fees 27,253 21,000 29.8 % Total Revenue from Adjusted Storage Rental Activities $2,897,372 $2,775,091 4.4 % Less: Storage Rental Expenses Storage Rent $405,223 $362,639 11.7 % Other Facility Costs 350,823 331,736 5.8 % Storage Rental Labor 27,719 25,140 10.3 % Other Storage Rental Expenses 41,417 40,342 2.7 % Storage Rental Cost of Sales $825,182 $759,857 8.6 % Storage Rental Gross Profit $2,072,190 $2,015,234 2.8 % Storage Rental Gross Margin 71.5 % 72.6 % (110 bps) Storage Rental Allocated Overhead 147,909 158,858 (6.9) % Total Storage Rental Adjusted EBITDA $1,924,265 $1,856,377 3.7 % Storage Rent 405,223 362,639 11.7 % Storage Rental Net Operating Income $2,329,504 $2,219,016 5.0 % Service Business Detail Total Service Revenue $1,621,412 $1,393,179 16.4 % Less: Terminations/Permanent Withdrawal Fees 27,253 21,000 29.8 % Total Revenue from Adjusted Service Activities $1,594,159 $1,372,179 16.2 % Less: Service Expenses Service Rent $11,605 $12,410 (6.5) % Other Facility Costs 28,111 24,894 12.9 % Service Labor 741,897 712,898 4.1 % Other Service Expenses 280,434 239,635 17.0 % Service Cost of Sales $1,062,047 $989,837 7.3 % Service Gross Profit $532,112 $382,342 39.2 % Service Gross Margin 33.4 % 27.9 % 550 bps Service Allocated Overhead 96,121 93,576 2.7 % Total Service Adjusted EBITDA $435,991 $288,766 51.0 % Section VI - Storage and Service Reconciliation investors.ironmountain.com Q4 2021 Supplemental Financial Information 22

Global Real Estate Portfolio and Lease Obligations Global Real Estate Portfolio (1) Owned Facilities Leased Facilities (2) Total Buildings Sq. Ft. Buildings Sq. Ft. Buildings Sq. Ft. Total as of 9/30/2021 (3) 273 25,465 1,191 69,486 1,464 94,951 Additions & Expansions — — 20 988 20 988 Dispositions & Move Outs (10) (583) (27) (727) (37) (1,310) Total as of 12/31/2021 (4) 263 24,883 1,184 69,746 1,447 94,629 Total % 18.2 % 26.3 % 81.8 % 73.7 % Top Five Markets Owned, United States (in Sq. Ft.) Top Five Markets Owned, International (in Sq. Ft.) Northern New Jersey 1,947 Paris, France 807 Chicago 1,282 Montreal, Canada 552 Boston 1,258 Mexico City, Mexico 452 Dallas 966 Toronto, Canada 434 Houston 917 Lima, Peru 434 Facility Lease Expirations (5) (% of total square feet subject to lease) 5.7% 4.1% 4.0% 5.3% 2.8% 2.3% 3.4% 5.3% 4.7% 62.4% 2022 2023 2024 2025 2026 2027 2028 2029 2030 Thereafter Weighted-Average Remaining Operating Lease Obligation: 11.3 Years (1) Includes real estate held in consolidated joint ventures. (2) Out of the 20 leased building additions and expansions, 8 were sale leasebacks. (3) Reflects adjustments to previous periods due to refinements to real estate basis. (4) Includes 11 owned data center facilities and 5 leased data center facilities with 2.7M Sq.Ft. and 0.6M Sq. Ft., respectively. (5) Includes financing and operating lease obligations. Section VII - Real Estate Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 23

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 2022 556 15.1 8.4% 47,646 14.7% 2023 350 22.7 12.6% 63,540 19.6% 2024 237 12.9 7.2% 32,704 10.1% 2025 77 20.0 11.1% 43,748 13.5% 2026 63 20.0 11.1% 33,746 10.4% 2027 10 3.2 1.8% 6,429 2.0% 2028 13 37.7 20.9% 47,216 14.6% Thereafter 14 48.5 26.9% 48,715 15.1% Total 1,320 180.1 100.0% $323,744 100.0% WALE: 4.0 years Data Center Leasing Activity Summary Q4 2021 Full Year 2021 Transaction Count GAAP MRR kW $ / kW / Month Transaction Count GAAP MRR kW $ / kW / Month New/expansion leases signed 30 $2,543 27,199 $93 168 $5,166 48,833 $106 Commenced leases 26 2,053 23,404 88 154 3,571 32,456 110 Renewed leases 80 873 3,559 245 403 3,798 14,781 257 Churn 0.8% 8.9% Cash Mark to Market 0.5% (0.2)% GAAP Mark to Market 2.8% 2.4% LON-2 Data Center Rendering (London, UK) Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 24

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 77.6% — — 14.2 77.6% Phoenix AZP-1 41.0 100.0% — — 41.0 100.0% AZP-2 22.0 100.0% — — 22.0 100.0% AZS-1 5.7 48.3% — — 5.7 48.3% Total Phoenix 68.7 95.7% — — 68.7 95.7% Denver DEN-1 11.3 57.3% — — 11.3 57.3% New Jersey NJE-1 15.1 100.0% 1.2 8.3% 16.3 93.3% Northern Virginia VA-1 12.4 100.0% — — 12.4 100.0% VA-2 4.0 100.0% 6.0 71.9% 10.0 83.1% Amsterdam AMS-1 12.7 83.5% 1.1 40.9% 13.8 80.1% London LON-1 9.1 92.8% — — 9.1 92.8% Frankfurt FRA-1 9.0 100.0% — — 9.0 100.0% FRA-2 2.4 100.0% — — 2.4 100.0% Singapore SIN-1 6.9 100.0% — — 6.9 100.0% India Web Werks JV 1.5 40.1% 0.8 — 2.3 26.3% Total Data Center Properties 167.3 91.2% 9.1 53.5% 176.4 89.3% Total Potential Capacity - Megawatts Q4 2021 Q4 2020 Leasable 176.4 129.8 Under Construction 55.1 49.9 Held for Development 372.2 196.4 Total Data Center Portfolio 603.6 376.1 Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 25

Data Center Expansion and Development Activity Project / Facilities MW Under Construction MW Pre- leased % Pre- Leased Investment in Q4 2021 ($M) Cumulative Investment ($M) Total Expected Investment ($M) Expected Completion Expected Stabilization MW Held for Development Data Center Expansion Amsterdam AMS-1 Phase 4 5.0 — — $0.5 $6.1 $45.0 Q1 2023 Q1 2024 4.6 Phoenix AZP-2 Phase 5 7.0 1.0 14.3% $13.5 $32.5 $100.0 Q4 2022 Q1 2023 19.0 Northern Virginia VA-2 Phase 3 12.0 12.0 100.0% $6.8 $6.8 $72.5 Q2 2022 Q2 2022 14.0 Frankfurt FRA-2 Phase 1 2.2 1.4 62.9% $4.2 $4.2 $9.6 Q1 2022 Q3 2022 6.0 India (2) Web Werks 0.7 — — — — — 1.6 All Other Facilities 23.6 Total Expansion 26.9 14.4 53.5% $25.1 $49.6 $227.1 68.8 New Development Amsterdam AMS-2 — — — — — — 10.6 Chicago CHI-2 — — — — — — 36.0 Frankfurt (1) FRA-1 Phase 2 9.0 9.0 100.0% — — — Q4 2022 Q2 2024 — FRA-1 Phase 3 9.0 9.0 100.0% — — — Q4 2022 Q4 2026 — London LON-2 Phase 1 9.0 — — $9.4 $17.5 $70.7 Q1 2023 Q1 2024 18.0 Northern Virginia VA Future Phases — — — — — — 222.0 India (2) Web Werks JV 1.2 — — — — — 16.8 Total New Development 28.2 18 63.8% $9.4 $17.5 $70.7 303.4 Total Development 55.1 32.4 58.8% $34.4 $67.1 $297.8 372.2 (1) FRA-1 is an unconsolidated joint venture; construction costs are funded by the Joint Venture with Iron Mountain managing the construction. (2) Represents an unconsolidated joint venture in India; operating three facilities in three markets. Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q4 2021 Supplemental Financial Information 26

Capitalization Senior Credit Facility Total Market Capitalization as of 12/31/2021 Capacity $1,953,125 # of Shares Outstanding 289,757 Outstanding $203,125 Share Price as of 12/31/21 $52.33 Letters of Credit $3,039 Total Market Capitalization $15,162,987 Remaining Capacity $1,746,961 Net Debt (1) $9,108,623 Interest Rate Spread (Prime) 0.75 % Total Enterprise Value $24,271,610 Interest Rate Spread (LIBOR) 1.75 % Net Debt to Total Enterprise Value 37.5 % Weighted Average Interest Rate 1.85 % Adjusted EBITDA to Interest Expense 3.9x Maturity Date 6/3/2023 Credit Facility Fixed Charge Coverage Ratio 2.4x Net Lease-Adjusted Leverage Ratio 5.3x Total Enterprise Value to Adjusted EBITDA (2) 14.8x Fixed vs. Floating Rate Debt 90% 10% Fixed Rate Debt Floating Rate Debt Credit Rating S&P Moody's Corporate BB- Ba3 Senior Credit Facility BB Ba3 Outlook Stable Stable Latest Update 12/10/2021 12/13/2021 Total Debt Weighted Average Rates Weighted Average Interest 4.8 % Weighted Average Maturity 7.1 Years USD denominated 82.8 % Debt Maturity Profile ($ in Millions) (3) $261 $396 $32 $547 $696 $1,000 $1,325 $1,000 $1,300 $1,100 $1,350 Senior Secured Credit Facility Bi-Lateral Loans AUD Term Loan B A/R Securitization USD Term Loan B Mortgage Securitization Senior Unsecured Notes 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 (1) Net debt is calculated as current portion of long-term debt of $309.4M plus long-term debt net of current portion of $8,962.5M plus deferred financing costs of $92.5M less cash and cash equivalents of $255.8M. (2) Total Enterprise Value to Adjusted EBITDA is calculated on a trailing twelve-month basis. (3) Excludes Deferred Financing Costs, Financing Leases, Notes Payable and Other. Section IX - Capitalization and Debt Maturity Profile investors.ironmountain.com Q4 2021 Supplemental Financial Information 27

Quarterly Capital Expenditures Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Growth: Data Center $99,604 $72,651 37.1 % $64,799 53.7 % Real Estate 51,883 21,033 146.7 % 21,336 143.2 % Innovation and Other 21,633 6,302 243.3 % 13,137 64.7 % Total Growth Capital Expenditures $173,120 $99,986 73.1 % $99,273 74.4 % Recurring: Real Estate $23,634 $13,587 73.9 % $22,765 3.8 % Non-Real Estate 15,669 20,497 (23.6) % 32,925 (52.4) % Data Center 6,411 3,913 63.9 % 7,876 (18.6) % Total Recurring Capital Expenditures $45,714 $37,995 20.3 % $63,567 (28.1) % Total Growth and Recurring Capital Expenditures $218,834 $137,981 58.6 % $162,840 34.4 % Net Change in Prepaid and Accrued Capital Expenditures (26,728) (14,591) 83.2 % (33,739) (20.8) % Total Cash Paid for Growth and Recurring Capital Expenditures $192,106 $123,390 55.7 % $129,101 48.8 % Full Year Capital Expenditures Full Year 2021 Full Year 2020 % Change Growth: Data Center $308,701 $216,491 42.6 % Real Estate 112,441 67,217 67.3 % Innovation and Other 37,078 18,810 97.1 % Total Growth Capital Expenditures $458,220 $302,518 51.5 % Recurring: Real Estate $67,032 $51,009 31.4 % Non-Real Estate 67,822 76,124 (10.9) % Data Center 13,347 15,959 (16.4) % Total Recurring Capital Expenditures $148,201 $143,092 3.6 % Total Growth and Recurring Capital Expenditures $606,421 $445,610 36.1 % Net Change in Prepaid and Accrued Capital Expenditures 4,661 (7,347) (163.4) % Total Cash Paid for Growth and Recurring Capital Expenditures $611,082 $438,263 39.4 % TTM Recurring Capex as a % of Revenue (excl. Data Center) 3.3% 3.5% 3.7% 3.7% 3.2% Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 TTM Data Center Recurring CapEx as a % of Data Center Revenue 5.7% 5.5% 5.0% 4.8% 4.1% Q4 2020 Q1 2021 Q2 2021 Q3 2021 Q4 2021 Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 28

Quarterly Business Acquisitions Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Business Acquisitions Business Acquisitions — $174,199 (100.0) % — — Change in Business Acquisition Accruals and Cash Acquired 246 (6,170) (104.0) % — — Total Cash Paid for Acquisitions, Net of Cash Acquired $246 $168,029 (99.9) % — — Full Year Business Acquisitions Full Year 2021 Full Year 2020 % Change Business Acquisitions Business Acquisitions $224,192 $118,496 89.2 % Change in Business Acquisition Accruals and Cash Acquired (20,194) 85 (23,857.4) % Total Cash Paid for Acquisitions, Net of Cash Acquired $203,998 $118,581 72.0 % Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 29

Quarterly Customer Acquisitions Q4 2021 Q3 2021 Q/Q % Change Q4 2020 Y/Y % Change Customer Acquisitions Acquisition of Customer Relationships — $2,747 (100.0) % — — Customer Inducements 2,254 1,330 69.5 % 2,375 (5.1) % Contract Fulfillment Costs 14,825 14,676 1.0 % 29,315 (49.4) % Total Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $17,079 $18,753 (8.9) % $31,690 (46.1) % Change in Customer Acquisition Accruals 1,092 (1,588) (168.7) % 817 33.6 % Total Cash Paid for Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $18,171 $17,165 5.9 % $32,507 (44.1) % Full Year Customer Acquisitions Full Year 2021 Full Year 2020 % Change Customer Acquisitions Acquisition of Customer Relationships $4,800 $1,734 176.8 % Customer Inducements 7,402 10,644 (30.5) % Contract Fulfillment Costs 58,524 60,020 (2.5) % Total Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $70,726 $72,398 (2.3) % Change in Customer Acquisition Accruals 1,092 2,612 (58.2) % Total Cash Paid for Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $71,818 $75,010 (4.3) % Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 30

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). 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, facility upgrade and system integration costs (collectively, "Acquisition and Integration Costs"). Acquisition and Integration Costs do not include costs associated with the formation of joint ventures or costs associated with the acquisition of customer relationships. 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 Charges; (iii) Intangible impairments; (iv) (Gain) loss on disposal/write-down of property, plant and equipment, net (including real estate); (v) Other (income) expense, net; (vi) Stock-based compensation expense; (vii) COVID-19 Costs; and (viii) Tax impact of reconciling items and discrete tax items. 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. 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 Charges; (iii) Intangible impairments; (iv) (Gain) loss on disposal/write-down of property, plant and equipment, net (including real estate); (v) Other (income) expense, net; (vi) Stock-based compensation expense; and (vii) COVID-19 Costs. Adjusted EBITDA Margin is calculated by dividing Adjusted EBITDA by total revenues. We also show Adjusted EBITDA and Adjusted EBITDA Margin for each of our reportable operating segments under “Results of Operations – Segment Analysis” in the 10-Q/10-K. 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. Adjusted EBITDA excludes both interest expense, net and the provision (benefit) for income taxes. These expenses are associated with our capitalization and tax structures, which we do not consider when evaluating the operating profitability of our core operations. Adjusted EBITDA also does not include depreciation and amortization expenses, in order to eliminate the impact of capital investments, which we evaluate by comparing capital expenditures to incremental revenue generated and as a percentage of total revenues. Adjusted EBITDA and Adjusted EBITDA Margin 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, net income (loss) or cash flows from operating activities (as determined in accordance with GAAP). Adjusted Funds From Operations, or AFFO: AFFO is defined as FFO (Normalized) (1) excluding (i) non-cash rent expense (income), (ii) depreciation on non-real estate assets, (iii) amortization expense associated with customer relationship value (CRV), intake costs, acquisitions of customer relationships and other intangibles, (other than capitalized internal commissions), (iv) amortization of deferred financing costs and debt discount/premium, (v) revenue reduction associated with amortization of permanent withdrawal fees 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: AFFO divided by weighted-average fully-diluted shares outstanding Funds From Operations, or FFO (Nareit), and FFO (Normalized): Funds from operations (“FFO”) is defined by the National Association of Real Estate Investment Trusts (“Nareit”) 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 and adjusting for our share of reconciling items from our unconsolidated joint ventures from FFO (“FFO (Nareit)”). FFO (Nareit) does not give effect to real estate depreciation because these amounts are computed, under GAAP, to allocate the 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). Although Nareit has published a definition of FFO, 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 Charges; (iii) Intangible impairments; (iv) (Gain) loss on disposal/write-down of property, plant and equipment, net (excluding real estate); (v) Other (income) expense, net; (vi) Stock-based compensation expense; (vii) COVID-19 Costs; (viii) Real estate financing lease depreciation; and (ix) Tax impact of reconciling items and discrete tax items. Section XI - Appendix and Definitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 31

FFO (Normalized) per share: FFO (Normalized) divided by weighted-average fully-diluted shares outstanding. Service Adjusted EBITDA: Service Adjusted EBITDA is calculated by taking service revenues excluding terminations and permanent withdrawals less direct expenses and overhead allocated to the service business. Terminations and permanent withdrawals are excluded from this calculation as they are included in the Storage NOI calculation. Storage Adjusted EBITDA: Storage Adjusted EBITDA is calculated by taking storage revenues including terminations and permanent withdrawal fees less direct expenses and overhead allocated to the storage business. Other Definitions Business Segments Global Record and Information Management ("Global RIM") Business: Provides (i) storage of physical records and healthcare information services, vital records services, courier operations, and the collection, handling and disposal of sensitive documents (collectively, “Records Management”) for customers in 63 countries around the globe, (ii) storage and rotation of backup computer media as part of corporate disaster recovery plans, including service and courier operations (“Data Protection & Recovery”); server and computer backup services; and related services offerings, (collectively, “Data Management”), (iii) Global Digital Solutions (“GDS”), which 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, primarily in the United States and Canada, (iv) Secure Shredding, which 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. Complementary to our shredding operations is the sale of the resultant waste paper to third-party recyclers. 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 throughout the United States, Canada and South Africa, (v) Secure IT Asset Disposition ("Secure ITAD"), a component of asset life cycle management, provides secure disposition of obsolete IT assets with: industry leading secure logistics and chain of custody practices, environmentally-responsible asset processing and recycling, and data sanitization and asset refurbishment services that enable value recovery through asset remarketing. Our service focuses on protecting and eradicating customer data while maintaining strong, audible, and transparent chain of custody practices. We are able to offer this service in over 30 countries, and (vi) on-demand, valet storage for consumers (“Consumer Storage”) across 31 markets in North America through a strategic partnership that utilizes 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. Our Global Data Center Business footprint spans nine markets in the United States: Denver, Colorado; Kansas City, Missouri; Boston, Massachusetts; Boyers, Pennsylvania; Manassas, Virginia; Edison, New Jersey; Columbus, Ohio; and Phoenix and Scottsdale, Arizona and seven international markets: Amsterdam, London, Singapore and, through unconsolidated joint ventures, Frankfurt, Mumbai, Pune and Noida. Corporate and Other Business: Consists primarily of Adjacent Businesses and other corporate items. Adjacent Businesses is comprised of (i) entertainment and media which helps 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, throughout the United States, Canada, France, China - Hong Kong S.A.R., and the United Kingdom (“Entertainment Services”) and (ii) technical expertise in the handling, installation and storing of art in the United States, Canada and Europe (“Fine Arts”). Our Corporate and Other Business segment also includes costs related to executive and staff functions, including finance, human resources and IT, which benefit the enterprise as a whole. 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 relatively small and discretionary in nature. We categorize our capital expenditures as follows: Growth Investment: Data Center - Expenditures primarily related to investments in new construction of data center facilities (including the acquisition of land and development of facilities) or capacity expansion in existing buildings. Real Estate - Expenditures primarily related to investments in land, buildings, building improvements, leasehold improvements and racking structures to grow our revenues or achieve operational efficiencies. Innovation & Other - Discretionary capital expenditures for significant new products and services, restructuring (including Project Summit), and integration of acquisitions. Recurring: Real Estate - Expenditures primarily related to the replacement of components of real estate assets such as buildings, building improvements, leasehold improvements and racking structures. Section XI - Appendix and Definitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 32

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. Data Center - Expenditures related to the upgrade or re-configuration of existing data center assets. Components of Overhead: Allocated Overhead – Includes overhead expenses directly associated with storage and service business operations allocated as follows: Field Operation Costs – Allocated to storage and service operations based on percent of revenue. Bad Debt Expenses – Allocated to storage and service operations based on percent of revenue. Transportation Costs – Allocated fully to service operations. Constant Currency: Adjusts results for normalized FX impacts in prior period. COVID-19 Costs: Costs that are incremental and directly attributable to the COVID-19 pandemic which are not expected to reoccur once the pandemic ends ("COVID-19 Costs"). These costs include the purchase of personal protective equipment for our employees and incremental cleaning costs of our facilities, among other direct costs. Bond Fixed Charge Coverage Ratio: Calculated as TTM Adjusted EBITDA divided by scheduled amortization, interest expense related to outstanding debt. Customer Inducements: Represents Free Move Costs and Permanent Withdrawal Fees. Data Center Business Definitions Leasable MW - Represents the amount of critical power capacity available for customer use, measured in megawatts. Leased % Calculation - Calculated as the megawatts under contract divided by the leasable megawatts. 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. Credit Facility Fixed Charge Coverage Ratio: Calculated as LTM Adjusted EBITDA plus rent expenses divided by scheduled amortization, interest expense related to outstanding debt and preferred equity, if any, and rent expenses. Net Lease-Adjusted Leverage Ratio: Calculated as net debt including the capitalized value of lease obligations plus six times rent expenses divided by EBITDA plus rent expenses. Organic Revenue Growth: Our organic revenue growth rate, which is a non-GAAP measure, 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: 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. Restructuring Charges: Operating expenditures associated with Project Summit, our transformation program announced in Q4 2019 which is designed to accelerate execution of Iron Mountain's Strategy. Storage Rev/NOI per Sq.Ft.: Storage revenue (or storage NOI) divided by the quarterly building sq ft average for storage products. Service Profit and Margin: The Gross Profit and Margin attributable to the worldwide service business. Calculated as follows: Services Adjusted EBITDA + Allocated Overhead Expenses = Service Profit ($) / Total Service Revenues (including Termination and Permanent Withdrawal Fees) = Service Margin (%) Storage Net Operating Income, or Storage NOI: Section XI - Appendix and Definitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 33

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 worldwide storage business. Calculated as follows: Storage Net Operating Income + Allocated Overhead Expenses - Storage Rent = Storage Profit ($) / Total Storage Revenues (excluding Termination and Permanent Withdrawal Fees) = Storage 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 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 Physical Storage Volume: Iron Mountain’s comprehensive portfolio of physical storage, including Records Management hardcopy records, data protection tapes, Consumer and Other, and Adjacent Businesses (Fine Art and Entertainment Services), measured on an absolute basis in cubic feet. Section XI - Appendix and Definitions investors.ironmountain.com Q4 2021 Supplemental Financial Information 34