Iron Mountain (IRM) 8-K Iron Mountain Reports Second Quarter Results

Supplemental Financial Information Second Quarter 2021 investors.ironmountain.com

Table of Contents Section I - Q2 Earnings Press Release 3 Q2 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 and Year-to-Date Operating Performance 10 Section V - Balance Sheets, Statements of Operations and Reconciliations Consolidated Balance Sheets 11 Consolidated Statements of Operations 12 Consolidated Statements of Operations Year-to-Date 13 Reconciliation of Net Income (Loss) to Adjusted EBITDA 14 Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share 15 Reconciliation of Net Income (Loss) to FFO and AFFO 16 Reconciliation of Net Income (Loss) to FFO and AFFO Year-to-Date 18 Section VI - Storage and Service Reconciliation Storage and Service Business Detail 20 Storage and Service Business Detail Year-to-Date 21 Section VII - Real Estate Metrics 22 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 23 Data Center Operating Portfolio 24 Data Center Expansion and Development Activity 25 Section IX - Capitalization and Debt Maturity Profile 26 Capitalization Debt Maturity Profile Section X - Capital Expenditures and Acquisitions Capital Expenditures and Investments 27 Capital Expenditures and Investments Year-to-Date 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 June 30, 2021 unless noted Unaudited investors.ironmountain.com Q2 2021 Supplemental Financial Information 2

Iron Mountain Reports Second Quarter Results -- Achieves record quarterly Revenue, Net Income and Adjusted EBITDA -- -- Increases midpoint of 2021 financial guidance -- -- Increases full-year Global Data Center leasing guidance to 30+ megawatts -- BOSTON – August 5, 2021 – Iron Mountain Incorporated (NYSE: IRM), the global leader in innovative storage and information management services, announces financial and operating results for the second quarter of 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. “Our stronger than expected performance in both the second quarter and first half of the year reflects the breadth and depth of our products and solutions and the strength of our deep customer relationships. Our second quarter results reflect increased demand for our services across our key markets,” said William L. Meaney, president and CEO of Iron Mountain. "As we celebrate and honor Iron Mountain's 70th anniversary this month, I am extremely proud of what our team has accomplished in spite of the continued challenges due to COVID. Our Mountaineers across the globe conquered every obstacle with tenacity, a relentless focus on accelerating growth and an innovative mindset." Financial Performance Highlights for the Second Quarter of 2021 and Year-To-Date 2021 ($ in millions, except per share data) Three Months Ended Year to Date 6/30/21 6/30/20 Y/Y % Change 6/30/21 6/30/20 Y/Y % Change Storage Rental Revenue $718 $677 6% $1,426 $1,361 5% Service Revenue $401 $305 32% $775 $690 12% Total Revenue $1,120 $982 14% $2,202 $2,051 7% Net Income/(Loss) $277 $(7) NM $323 $58 459% Adjusted EBITDA $406 $359 13% $786 $725 8% Adjusted EBITDA Margin 36.2% 36.6% -40 bps 35.7% 35.4% +30 bps AFFO $246 $250 (1)% $481 $480 — AFFO per share $0.85 $0.87 (3)% $1.66 $1.67 — • Total reported Revenues for the second quarter were $1.12 billion, compared with $982.2 million in the second quarter of 2020, an increase of 14.0%. Excluding the impact of foreign currency exchange (FX), total reported Revenues increased 10.2% compared to the prior year, driven by a 26.9% increase in Service revenue, while Storage rental revenue increased 2.7%. Year to date, total reported Revenues increased 7.4%, or 4.6%, excluding the impact of FX. • The Global Data Center business revenue increased 15.3% in the second quarter, or 13.3% year over year, excluding the impact of FX. Through June 30, 2021, Iron Mountain has executed 12.6 megawatts of new and expansion leasing, and is increasing its outlook for full- year data center leasing to greater than 30 megawatts from previous guidance of 25 to 30 megawatts, based on the strength of its first-half performance and pipeline. • Net Income for the second quarter was $276.5 million compared with a Net Loss of $7.1 million in the second quarter of 2020. The following items were included in Net Income: ◦ Restructuring Charges of $39.4 million associated with the implementation of Project Summit compared to $39.3 million, in the second quarters of 2021 and 2020, respectively. ◦ Gain on Disposal/Write-Down of PP&E, Net of $128.9 million compared to $1.3 million, in the second quarters of 2021 and 2020, respectively, primarily related to the company's capital recycling program. ◦ Other Income, Net of $186.2 million in the second quarter of 2021, primarily related to a gain on sale from the divestment of the company's Intellectual Property Management business, compared to Other Expense, Net of $25.7 million in the second quarter of 2020, primarily related to a debt extinguishment charge of $17.0 million. • Year to date, Net Income was $323.2 million, compared with $57.8 million in 2020. The following items were included in Net Income: ◦ Restructuring Charges of $79.3 million compared to $80.3 million year to date 2021 and 2020, respectively. Section I - Q2 Earnings Press Release investors.ironmountain.com Q2 2021 Supplemental Financial Information 3

◦ 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 $133.4 million compared to $2.3 million, year to date 2021 and 2020, respectively, primarily related to the company's capital recycling program. ◦ Other Income, Net of $181.5 million year to date 2021, primarily related to a gain on sale from the divestment of the company's Intellectual Property Management business, compared to Other Income, Net of $17.0 million year to date 2020, primarily related to a Foreign Currency Transaction Gain of $35.9 million, partially offset by a debt extinguishment charge of $17.0 million. • Adjusted EBITDA for the second quarter was $405.6 million, compared with $359.5 million in the second quarter of 2020, an increase of 12.8%. On a constant currency basis, Adjusted EBITDA increased by 9.0%, driven by the strong increase in Service revenue, benefits from Project Summit and the flow through from revenue management. Year to date, Adjusted EBITDA was $786.2 million, compared with $725.5 million in 2020, an increase of 8.4%. On a constant currency basis, Adjusted EBITDA increased 5.5%. • Reported EPS - Fully Diluted from Net Income (Loss) for the second quarter was $0.95, compared with $(0.02) in the second quarter of 2020. Year to date, Reported EPS - Fully Diluted from Net Income (Loss) was $1.11, compared with $0.20 in 2020. • Adjusted EPS for the second quarter was $0.38, compared with $0.27 in the second quarter of 2020. Adjusted EPS reflects a structural tax rate of 16.2% and 16.7%, in the second quarters of 2021 and 2020, respectively. Year to date, Adjusted EPS was $0.70, compared with $0.55 in 2020. • FFO (Normalized) per share was $0.69 for the second quarter, compared with $0.58 in the second quarter of 2020, an increase of 19.0%. Year to date, FFO (Normalized) per share was $1.32, compared with $1.17 in 2020, or an increase of 12.0%. • AFFO was $246.0 million for the second quarter, compared with $249.7 million in the second quarter of 2020, or a decrease of 1.5%. Year to date, AFFO was $481.4 million, compared with $480.3 million in 2020, or an increase of 0.2%. AFFO in the second quarter and year-to- date 2020 includes previously disclosed tax refunds in the amount of $22.5 million and $27.5 million, respectively. Excluding the benefit of the tax refunds, AFFO in the second quarter and year-to-date 2021 would have increased 8.3% and 6.3% year over year, respectively. • AFFO per share was $0.85 for the second quarter, compared with $0.87 in the second quarter of 2020, or a decrease of 2.5%. Year to date, AFFO per share was $1.66, compared with $1.67 in 2020, or a decrease of 0.5%. Excluding the aforementioned tax refunds, AFFO per share in the second quarter and year-to-date 2021 would have increased 7.7% and 5.6%, respectively. Dividend On August 5, 2021, Iron Mountain's board of directors declared a quarterly cash dividend of $0.6185 per share for the third quarter. The third- quarter 2021 dividend is payable on October 6, 2021, for shareholders of record on September 15, 2021. Guidance Reflecting outperformance in the first half of the year and positive momentum in the business, Iron Mountain has increased the midpoint of its financial guidance; details are summarized in the table below. 2021 Guidance(1) ($ in millions, except per share data) New Y/Y % Change Previous Y/Y % Change Total Revenue $4,415 - $4,515 6% - 9% $4,365 - $4,515 5% - 9% Adjusted EBITDA $1,600 - $1,635 8% - 11% $1,585 - $1,635 7% - 11% AFFO $970 - $1,005 9% - 13% $955 - $1,005 8% - 13% AFFO Per Share $3.33 - $3.45 8% - 12% $3.28 - $3.45 7% - 12% (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 the global leader in innovative storage and information management services, storing and protecting billions of valued assets, including critical business information, highly sensitive data, and cultural and historical artifacts. 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, 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 - Q2 Earnings Press Release investors.ironmountain.com Q2 2021 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 operations, economic performance, financial condition, goals, beliefs, future growth strategies, investment objectives, plans and current expectations, such as our (1) 2021 guidance as well as our expectations for growth, including growth opportunities and growth rates for revenue by segment, organic revenue, organic volume and other metrics, (2) expectations and assumptions regarding the impact from the COVID-19 pandemic on us and our customers, including on our businesses, financial position, results of operations and cash flows, (3) expected benefits, costs and actions related to, and timing of, Project Summit, (4) expectations as to our capital allocation strategy, including our future investments, leverage ratio, dividend payments and possible funding sources (including real estate monetization) and capital expenditures, (5) expectations regarding the closing of pending acquisitions and investments, and (6) 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” 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 execute on Project Summit and the potential impacts of Project Summit on our ability to retain and recruit employees; (iii) our ability to remain qualified for taxation as a real estate investment trust for United States federal income tax purposes; (iv) 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; (v) 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; (vi) changes in the amount of our capital expenditures; (vii) our ability to raise debt or equity capital and changes in the cost of our debt; (viii) 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; (ix) 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 systems and the impact of such incidents on our reputation and ability to compete; (x) changes in the price for our storage and information management services relative to the cost of providing such storage and information management services; (xi) 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; (xii) our ability to comply with our existing debt obligations and restrictions in our debt instruments; (xiii) the impact of service interruptions or equipment damage and the cost of power on our data center operations; (xiv) the cost or potential liabilities associated with real estate necessary for our business; (xv) failures in our adoption of new IT systems; (xvi) unexpected events, including those from climate change (xvii) other trends in competitive or economic conditions affecting our financial condition or results of operations not presently contemplated; and (xviii) 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 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: Greer Aviv, 617-535-2887 Sarah Barry, 617-237-6597 Senior Vice President, Investor Relations Manager, Investor Relations greer.aviv@ironmountain.com sarah.barry@ironmountain.com Section I - Q2 Earnings Press Release investors.ironmountain.com Q2 2021 Supplemental Financial Information 5

Facts and Figures $4.3 Billion Trailing Twelve-Month Revenue 225,000+ Customer Accounts ~24,000 Employees ~1,450 Facilities Worldwide 89 million+ Pieces of Media ~730 million Cubic Feet of Global Storage Volume Revenue and Gross Profit Mix Geographic Revenue Mix 66% 20% 5% 9% North America Europe Latin America Asia Business Revenue Mix 64% 36% Storage Rental Service Business Adjusted Gross Profit Mix 80% 20% Storage Rental Service Product Revenue Mix 61% 11% 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 Q2 2021 Supplemental Financial Information 6

Financial Highlights Q2 2021 Q1 2021 Q4 2020 Q3 2020 Q2 2020 Storage Rental Revenue $718,272 $708,056 $697,294 $696,294 $676,956 Service Revenue $401,484 $373,984 $362,359 $340,353 $305,283 Total Revenues $1,119,756 $1,082,040 $1,059,653 $1,036,647 $982,239 Adjusted EBITDA $405,631 $380,565 $374,247 $376,012 $359,462 Adjusted EBITDA Margin 36.2 % 35.2 % 35.3 % 36.3 % 36.6 % Net Income (Loss) Attributable to Iron Mountain Incorporated $275,285 $45,603 $247,411 $38,394 $(7,086) Reported EPS - Fully Diluted $0.95 $0.16 $0.86 $0.13 $(0.02) Adjusted EPS $0.38 $0.32 $0.29 $0.33 $0.27 FFO (Normalized) $199,963 $181,338 $173,483 $181,660 $166,174 FFO (Normalized) per Share $0.69 $0.63 $0.60 $0.63 $0.58 AFFO $245,992 $235,391 $190,771 $216,420 $249,694 AFFO per Share $0.85 $0.81 $0.66 $0.75 $0.87 Dividend per Share $0.62 $0.62 $0.62 $0.62 $0.62 TTM AFFO Payout Ratio 80.7 % 80.1 % 80.4 % 76.7 % 75.6 % Weighted Average Common Shares Outstanding - Diluted 291,079 289,528 289,161 288,811 288,071 Net Lease-Adjusted Leverage Ratio 5.3x 5.5x 5.3x 5.3x 5.4x Operating Highlights Q2 2021 Q1 2021 Q4 2020 Q3 2020 Q2 2020 Organic Storage Rental Revenue Growth 2.5 % 1.7 % 1.7 % 2.5 % 2.3 % Organic Service Revenue Growth 25.5 % (4.8) % (12.1) % (13.5) % (23.1) % Total Volume - Storage 733,086 728,616 726,430 726,649 724,411 Storage Facility Capacity Utilization 84.0 % 82.3 % 81.9 % 82.3 % 82.4 % Records Management Retention Rate 94.4 % 94.4 % 93.7 % 94.1 % 93.7 % Storage Revenue / Sq. Ft $7.93 $7.88 $7.78 $7.76 $7.49 Storage NOI / Sq. Ft $6.43 $6.33 $6.16 $6.36 $6.04 Data Center: Leasable Megawatts 144.7 136.4 129.8 126.3 122.3 Leased % - Stabilized 88.4 % 88.5 % 89.0 % 92.1 % 89.8 % Leased % - Total 83.0 % 85.2 % 87.4 % 91.8 % 89.5 % Kilowatts Leased - New/Expansion 3,610 9,035 7,435 12,303 32,355 Churn 1.9 % 2.3 % 3.9 % 1.6 % 0.8 % Number of Facilities 15 15 15 15 14 Number of Markets 13 13 13 13 13 Section III - Financial Highlights investors.ironmountain.com Q2 2021 Supplemental Financial Information 7

Organic Revenue Growth (1) Q2 2021 Q1 2021 YTD 2021 Reported Constant Currency Organic Revenue Reported Constant Currency Organic Revenue Reported Constant Currency Organic Revenue Storage Rental 6.1% 2.7% 2.5% 3.6% 1.9% 1.7% 4.8% 2.3% 2.1% Service 31.5% 26.9% 25.5% (2.9)% (4.8)% (4.8)% 12.3% 9.4% 8.7% Total Revenues 14.0% 10.2% 9.7% 1.2% (0.5)% (0.6)% 7.4% 4.6% 4.3% Total Organic Revenue Growth 0.7% 1.3% 1.0% (7.2)% (3.4)% (3.4)% (0.6)% 9.7% Q3 2019 Q4 2019 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 (8.0)% (4.0)% 0.0% 4.0% 8.0% 12.0% Organic Storage Rental Revenue Growth 3.0% 2.5% 3.0% 2.3% 2.5% 1.7% 1.7% 2.5% Q3 2019 Q4 2019 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 0.0% 2.0% 4.0% 6.0% Organic Service Revenue Growth (3.0)% (0.7)% (2.3)% (23.1)% (13.5)% (12.1)% (4.8)% 25.5% Q3 2019 Q4 2019 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 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 Q2 2021 Supplemental Financial Information 8

Worldwide Storage Volume Records and Information Management Adjacent Businesses Consumer and Other Q3 2019 Q4 2019 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 600,000 620,000 640,000 660,000 680,000 700,000 720,000 740,000 Q3 2019 Q4 2019 Q1 2020 Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Records and Information Management 696,850 694,614 712,388 712,009 711,148 708,981 708,587 710,790 Adjacent Businesses 5,507 5,508 5,938 5,906 6,534 7,077 7,335 7,683 Consumer and Other 3,805 4,096 4,308 6,495 8,967 10,373 12,694 14,613 Total 706,162 704,218 722,634 724,411 726,649 726,430 728,616 733,086 Business acquisitions during the quarter (1) 202 514 18,389 3,555 272 — — 5,020 (1) Business acquisitions volume acquired during the quarter included in total volume. Section IV - Operational Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 9

Second Quarter 2021 Y/Y % Change Q2 2021 Q1 2021 Q2 2020 Reported Constant Currency Organic Growth (2) Global RIM Business Storage Rental $617,078 $610,694 $584,402 5.6% 1.9% 1.6% Service 375,854 356,600 292,700 28.4% 24.0% 24.0% Total Revenues $992,932 $967,294 $877,102 13.2% 9.3% 9.1% Adjusted EBITDA $430,308 $408,562 $383,816 Adjusted EBITDA Margin 43.3 % 42.2 % 43.8 % Global Data Center Business Data Center Revenue (1) $76,977 $71,108 $66,768 15.3% 13.3% 13.3% Adjusted EBITDA $33,432 $30,432 $30,558 Adjusted EBITDA Margin 43.4 % 42.8 % 45.8 % Corporate and Other Business Storage Rental $29,957 $30,205 $28,742 4.2% 2.9% 5.2% Service 19,890 13,433 9,627 106.6% 93.8% 50.3% Total Revenues $49,847 $43,638 $38,369 29.9% 26.5% 17.7% Adjusted EBITDA $(58,109) $(58,429) $(54,912) Total Consolidated Storage Rental $718,272 $708,056 $676,956 6.1% 2.7% 2.5% Service $401,484 373,984 305,283 31.5% 26.9% 25.5% Total Revenues $1,119,756 $1,082,040 $982,239 14.0% 10.2% 9.7% Adjusted EBITDA $405,631 $380,565 $359,462 Adjusted EBITDA Margin 36.2 % 35.2 % 36.6 % Year to Date 2021 Y/Y % Change YTD 2021 YTD 2020 Reported Constant Currency Organic Growth (2) Global RIM Business Storage Rental $1,227,772 $1,174,415 4.5% 1.8% 1.6% Service 732,454 659,106 11.1% 8.3% 8.2% Total Revenues $1,960,226 $1,833,521 6.9% 4.1% 4.0% Adjusted EBITDA $838,870 $775,787 Adjusted EBITDA Margin 42.8 % 42.3 % Global Data Center Business Data Center Revenue (1) $148,085 $134,125 10.4% 8.6% 8.6% Adjusted EBITDA $63,864 $61,454 Adjusted EBITDA Margin 43.1 % 45.8 % Corporate and Other Business Storage Rental $60,162 $57,681 4.3% 3.1% 4.3% Service 33,323 25,643 29.9% 24.8% 8.0% Total Revenues $93,485 $83,324 12.2% 9.9% 5.5% Adjusted EBITDA $(116,538) $(111,780) Total Consolidated Storage Rental $1,426,328 $1,360,503 4.8% 2.3% 2.1% Service 775,468 690,467 12.3% 9.4% 8.7% Total Revenues $2,201,796 $2,050,970 7.4% 4.6% 4.3% Adjusted EBITDA $786,196 $725,461 Adjusted EBITDA Margin 35.7 % 35.4 % (1) Includes Global Data Center service revenue of $5.7M, $4.0M, and $3.0M in Q2 2021, Q1 2021, and Q2 2020, respectively, and $9.7M and $5.7M for YTD 2021 and YTD 2020 respectively. (2) Constant Currency and excluding impact from business acquisitions and divestitures. Section IV - Operational Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 10

Consolidated Balance Sheets 6/30/2021 12/31/2020 ASSETS Current Assets: Cash and Cash Equivalents $315,928 $205,063 Accounts Receivable, Net 852,449 859,344 Prepaid Expenses and Other 222,231 205,380 Total Current Assets $1,390,608 $1,269,787 Property, Plant and Equipment: Property, Plant and Equipment $8,319,083 $8,246,337 Less: Accumulated Depreciation (3,863,477) (3,743,894) Property, Plant and Equipment, Net $4,455,606 $4,502,443 Other Assets, Net: Goodwill $4,508,754 $4,557,609 Customer Relationships, Customer Inducements and Data Center Lease-Based Intangibles 1,256,181 1,326,977 Operating Lease Right-of-use Assets 2,342,197 2,196,502 Other 360,970 295,949 Total Other Assets, Net $8,468,102 $8,377,037 Total Assets $14,314,316 $14,149,267 LIABILITIES AND EQUITY Current Liabilities: Current Portion of Long-term Debt $106,274 $193,759 Accounts Payable 321,286 359,863 Accrued Expenses and Other Current Liabilities 1,064,397 1,146,288 Deferred Revenue 256,245 295,785 Total Current Liabilities $1,748,202 $1,995,695 Long-term Debt, Net of Current Portion 8,760,728 8,509,555 Long-term Operating Lease Liabilities, Net of Current Portion 2,186,625 2,044,598 Other Long-term Liabilities (1) 471,019 462,690 Total Long-term Liabilities $11,418,372 $11,016,843 Total Liabilities $13,166,574 $13,012,538 Equity Total Equity $1,147,742 $1,136,729 Total Liabilities and Equity $14,314,316 $14,149,267 (1) Includes redeemable noncontrolling interests of $64.7M and $59.8M as of June 30, 2021 and December 31, 2020, respectively. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 11

Quarterly Consolidated Statements of Operations Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Revenues: Storage Rental $718,272 $708,056 1.4 % $676,956 6.1 % Service 401,484 373,984 7.4 % 305,283 31.5 % Total Revenues $1,119,756 $1,082,040 3.5 % $982,239 14.0 % Operating Expenses: Cost of Sales (excluding Depreciation and Amortization) (1) $474,579 $451,909 5.0 % $406,693 16.7 % Selling, General and Administrative (2) 259,779 258,723 0.4 % 241,947 7.4 % Depreciation and Amortization 166,685 165,642 0.6 % 163,850 1.7 % Acquisition and Integration Costs 2,277 — — — — % Restructuring Charges 39,443 39,811 (0.9) % 39,298 0.4 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (128,935) (4,451) 2,797.0 % (1,275) 10,015.0 % Total Operating Expenses $813,828 $911,634 (10.7) % $850,513 (4.3) % Operating Income (Loss) $305,928 $170,406 79.5 % $131,726 132.2 % Interest Expense, Net 105,220 104,422 0.8 % 103,456 1.7 % Other (Income) Expense, Net (186,230) 4,713 (4,051.2) % 25,700 (824.6) % Net Income (Loss) Before Provision (Benefit) for Income Taxes $386,938 $61,271 531.5 % $2,570 14,953.6 % Provision (Benefit) for Income Taxes 110,416 14,640 654.2 % 9,683 1,040.3 % Net Income (Loss) $276,522 $46,631 493.0 % $(7,113) (3,987.6) % Less: Net Income (Loss) Attributable to Noncontrolling Interests 1,237 1,028 20.4 % (27) (4,734.1) % Net Income (Loss) Attributable to Iron Mountain Incorporated $275,285 $45,603 503.7 % $(7,086) (3,984.8) % Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated: Basic $0.95 $0.16 493.8 % $(0.02) (4,850.0) % Diluted $0.95 $0.16 493.8 % $(0.02) (4,850.0) % Weighted Average Common Shares Outstanding - Basic 289,247 288,756 0.2 % 288,071 0.4 % Weighted Average Common Shares Outstanding - Diluted 291,079 289,528 0.5 % 288,071 1.0 % (1) Includes $7.6M of direct and incremental costs related to COVID-19 in Q2 2020. (2) Includes $1.6M of direct and incremental costs related to COVID-19 in Q2 2020. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 12

Year to Date Consolidated Statement of Operations YTD 2021 YTD 2020 % Change Revenues: Storage Rental $1,426,328 $1,360,503 4.8 % Service 775,468 690,467 12.3 % Total Revenues $2,201,796 $2,050,970 7.4 % Operating Expenses: Cost of Sales (excluding Depreciation and Amortization) (1) $926,488 $873,614 6.1 % Selling, General and Administrative (2) 518,502 480,680 7.9 % Depreciation and Amortization 332,327 326,434 1.8 % Acquisition and Integration Costs 2,277 — — Restructuring Charges 79,254 80,344 (1.4) % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (133,386) (2,330) 5,624.7 % Total Operating Expenses $1,725,462 $1,781,742 (3.2) % Operating Income (Loss) $476,334 $269,228 76.9 % Interest Expense, Net 209,642 209,105 0.3 % Other (Income) Expense, Net (181,517) (17,026) 966.1 % Net Income (Loss) Before Provision (Benefit) for Income Taxes $448,209 $77,149 481.0 % Provision (Benefit) for Income Taxes 125,056 19,370 545.6 % Net Income (Loss) $323,153 $57,779 459.3 % Less: Net Income (Loss) Attributable to Noncontrolling Interests 2,265 890 154.5 % Net Income (Loss) Attributable to Iron Mountain Incorporated $320,888 $56,889 464.1 % Net Income (Loss) Per Share Attributable to Iron Mountain Incorporated: Basic $1.11 $0.20 455.0 % Diluted $1.11 $0.20 455.0 % Weighted Average Common Shares Outstanding - Basic 289,001 287,955 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,303 288,301 0.7 % (1) Includes $7.6M of direct and incremental costs related to COVID-19 in YTD 2020. (2) Includes $1.6M of direct and incremental costs related to COVID-19 in YTD 2020. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 13

Quarterly Reconciliation of Net Income (Loss) to Adjusted EBITDA Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Net Income (Loss) $276,522 $46,631 493.0 % $(7,113) (3,987.6) % Add / (Deduct): Interest Expense, Net 105,220 104,422 0.8 % 103,456 1.7 % Provision (Benefit) for Income Taxes 110,416 14,640 654.2 % 9,683 1,040.3 % Depreciation and Amortization 166,685 165,642 0.6 % 163,850 1.7 % Acquisition and Integration Costs 2,277 — — — — Restructuring Charges 39,443 39,811 (0.9) % 39,298 0.4 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (128,935) (4,451) 2,796.8 % (1,275) 10,012.5 % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (189,605) 2,121 (9,039.4) % 23,239 (915.9) % Stock-Based Compensation Expense 22,536 10,733 110.0 % 18,880 19.4 % COVID-19 Costs — — — 9,285 (100.0) % Our Share of Adjusted EBITDA Reconciling Items from our Unconsolidated Joint Ventures 1,072 1,016 5.5 % 159 574.2 % Adjusted EBITDA $405,631 $380,565 6.6 % $359,462 12.8 % Year to Date Reconciliation of Net Income (Loss) to Adjusted EBITDA YTD 2021 YTD 2020 % Change Net Income (Loss) $323,153 $57,779 459.3 % Add / (Deduct): Interest Expense, Net 209,642 209,105 0.3 % Provision (Benefit) for Income Taxes 125,056 19,370 545.6 % Depreciation and Amortization 332,327 326,434 1.8 % Acquisition and Integration Costs 2,277 — — Restructuring Charges 79,254 80,344 (1.4) % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Including Real Estate) (133,386) (2,330) 5,624.7 % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (187,484) (21,792) 760.3 % Stock-Based Compensation Expense 33,269 23,991 38.7 % COVID-19 Costs — 9,285 (100.0) % Our Share of Adjusted EBITDA Reconciling Items from our Unconsolidated Joint Ventures 2,088 275 659.3 % Adjusted EBITDA $786,196 $725,461 8.4 % Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 14

Quarterly Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.95 $0.16 493.8 % $(0.02) n/a Add / (Deduct): Acquisition and Integration Costs 0.01 — — — — Restructuring Charges 0.14 0.14 — 0.14 — (Gain) Loss on Disposal/Write-Down of PP&E, Net (0.44) (0.02) 2,100.0 % — — Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (0.65) 0.01 (6,600.0) % 0.08 (912.5) % Stock-Based Compensation Expense 0.08 0.04 100.0 % 0.07 14.3 % COVID-19 Costs — — — 0.03 (100.0) % Tax Impact of Reconciling Items and Discrete Tax Items (1) 0.31 (0.01) (3,200.0) % (0.02) n/a Adjusted EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.38 $0.32 18.8 % $0.27 40.7 % Year to Date Reconciliation of Reported Earnings per Share to Adjusted Earnings per Share YTD 2021 YTD 2020 % Change Reported EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $1.11 $0.20 455.0 % Add / (Deduct): Acquisition and Integration Costs 0.01 — — Restructuring Charges 0.27 0.28 (3.6) % Intangible Impairments — 0.08 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (0.46) (0.01) 4,500.0 % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (0.65) (0.08) 712.5 % Stock-Based Compensation Expense 0.11 0.08 37.5 % COVID-19 Costs — 0.03 (100.0) % Tax Impact of Reconciling Items and Discrete Tax Items (1) 0.30 (0.04) (850.0) % Income (Loss) Attributable to Noncontrolling Interests 0.01 — — Adjusted EPS - Fully Diluted from Net Income (Loss) Attributable to Iron Mountain Incorporated $0.70 $0.55 27.3 % (1) The difference between our effective tax rates and our structural tax rate (or adjusted effective tax rates) for the quarters ended June 30, 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 quarter ended June 30, 2021, quarter ended March 31, 2021, and quarter ended June 30, 2020 was 16.2%, 16.6% and 16.7%, respectively. 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 Q2 2021 Supplemental Financial Information 15

Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Net Income $276,522 $46,631 493.0 % $(7,113) (3,987.6) % Add / (Deduct): Real Estate Depreciation (1) 74,784 76,047 (1.7) % 75,719 (1.2) % Gain on Sale of Real Estate, Net of Tax (102,476) (4,305) 2,280.2 % (1,089) 9,308.3 % Data Center Lease-Based Intangible Asset Amortization (2) 10,482 10,483 — 10,379 1.0 % FFO (Nareit) $259,312 $128,856 101.2 % $77,896 232.9 % Add / (Deduct): Acquisition and Integration Costs 2,277 — — — — Restructuring Charges 39,443 39,811 (0.9) % 39,298 0.4 % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Excluding Real Estate) (1,076) (146) 634.6 % (155) 595.8 % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (189,605) 2,121 (9,037.5) % 23,239 (915.9) % Stock-Based Compensation Expense 22,536 10,733 110.0 % 18,880 19.4 % COVID-19 Costs — — — 9,285 (100.0) % Real Estate Financing Lease Depreciation 3,515 3,536 (0.6) % 3,431 2.4 % Tax Impact of Reconciling Items and Discrete Tax Items (3) 63,570 (3,569) (1,881.2) % (5,690) (1,217.2) % Our Share of FFO (Normalized) Reconciling Items from our Unconsolidated Joint Ventures (9) (4) 109.5 % (10) (10.0) % FFO (Normalized) $199,963 $181,338 10.3 % $166,174 20.3 % Per Share Amounts (Fully Diluted Shares): FFO (Nareit) $0.89 $0.45 97.8 % $0.27 229.6 % FFO (Normalized) $0.69 $0.63 9.5 % $0.58 19.0 % Weighted Average Common Shares Outstanding - Basic 289,247 288,756 0.2 % 288,071 0.4 % Weighted Average Common Shares Outstanding - Diluted 291,079 289,528 0.5 % 288,071 1.0 % (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 Q2 2021 Supplemental Financial Information 16

Quarterly Reconciliation of Net Income (Loss) to FFO and AFFO (Continued) Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change FFO (Normalized) $199,963 $181,338 10.3 % $166,174 20.3 % Add / (Deduct): Non-Real Estate Depreciation 34,191 34,866 (1.9) % 33,779 1.2 % Amortization Expense (1) 36,250 33,486 8.3 % 34,526 5.0 % Amortization of Deferred Financing Costs 4,316 4,127 4.6 % 4,488 (3.8) % Revenue Reduction Associated with Amortization of Permanent Withdrawal Fees and Above - and Below-Market Leases 2,065 2,263 (8.7) % 2,566 (19.5) % Non-Cash Rent Expense (Income) 3,958 5,410 (26.8) % 2,952 34.1 % Reconciliation to Normalized Cash Taxes 188 1,574 (88.1) % 29,502 (99.4) % Our Share of AFFO Reconciling Items from our Unconsolidated Joint Ventures 969 911 6.4 % 77 1,131.1 % Less: Recurring Capital Expenditures 35,909 28,583 25.6 % 24,369 47.4 % AFFO $245,992 $235,391 4.5 % $249,694 (1.5) % Per Share Amounts (Fully Diluted Shares): AFFO Per Share $0.85 $0.81 3.9 % $0.87 (2.5) % Weighted Average Common Shares Outstanding - Basic 289,247 288,756 0.2 % 288,071 0.4 % Weighted Average Common Shares Outstanding - Diluted 291,079 289,528 0.5 % 288,071 1.0 % (1) Includes Customer Relationship Value, intake costs, acquisition of customer relationships, and other intangibles. Excludes amortization of capitalized commissions of $7.5M, $7.2M, and $6.0M in Q2 2021, Q1 2021, and Q2 2020, respectively. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 17

Year to Date Reconciliation of Net Income (Loss) to FFO and AFFO YTD 2021 YTD 2020 % Change Net Income $323,153 $57,779 459.3 % Add / (Deduct): Real Estate Depreciation (1) 150,831 152,306 (1.0) % Gain on Sale of Real Estate, Net of Tax (106,781) (1,581) 6,655.4 % Data Center Lease-Based Intangible Asset Amortization (2) 20,965 21,732 (3.5) % FFO (Nareit) $388,168 $230,236 68.6 % Add / (Deduct): Acquisition and Integration Costs 2,277 — — Restructuring Charges 79,254 80,344 (1.4) % Intangible Impairments — 23,000 (100.0) % (Gain) Loss on Disposal/Write-Down of PP&E, Net (Excluding Real Estate) (1,222) (399) 206.2 % Other (Income) Expense, Net, Excluding our Share of Losses (Gains) from our Unconsolidated Joint Ventures (187,484) (21,792) 760.3 % Stock-Based Compensation Expense 33,269 23,991 38.7 % COVID-19 Costs — 9,285 (100.0) % Real Estate Financing Lease Depreciation 7,051 6,594 6.9 % Tax Impact of Reconciling Items and Discrete Tax Items (3) 60,494 (12,613) (579.6) % Our Share of FFO (Normalized) Reconciling Items from our Unconsolidated Joint Ventures (13) (30) (55.7) % FFO (Normalized) $381,794 $338,616 12.8 % Per Share Amounts (Fully Diluted Shares): FFO (Nareit) $1.34 $0.80 67.4 % FFO (Normalized) $1.32 $1.17 12.0 % Weighted Average Common Shares Outstanding - Basic 289,001 287,955 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,303 288,301 0.7 % (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 Q2 2021 Supplemental Financial Information 18

Year to Date Reconciliation of Net Income (Loss) to FFO and AFFO (Continued) YTD 2021 YTD 2020 % Change FFO (Normalized) $381,794 $338,616 12.8 % Add / (Deduct): Non-Real Estate Depreciation 69,057 67,728 2.0 % Amortization Expense (1) 69,736 66,433 5.0 % Amortization of Deferred Financing Costs 8,443 9,001 (6.2) % Revenue Reduction Associated with Amortization of Permanent Withdrawal Fees and Above - and Below-Market Leases 4,327 5,248 (17.5) % Non-Cash Rent Expense (Income) 9,369 5,497 70.4 % Reconciliation to Normalized Cash Taxes 1,269 31,785 (96.0) % Our Share of AFFO Reconciling Items from our Unconsolidated Joint Ventures 1,881 151 1,145.5 % Less: Recurring Capital Expenditures 64,492 44,112 46.2 % AFFO $481,384 $480,348 0.2 % Per Share Amounts (Fully Diluted Shares): AFFO Per Share $1.66 $1.67 (0.5) % Weighted Average Common Shares Outstanding - Basic 289,001 287,955 0.4 % Weighted Average Common Shares Outstanding - Diluted 290,303 288,301 0.7 % (1) Includes Customer Relationship Value, intake costs, acquisition of customer relationships, and other intangibles. Excludes amortization of capitalized commissions of $14.7M and $11.6M, in YTD 2021 and 2020, respectively. Section V - Balance Sheets, Statements of Operations and Reconciliations investors.ironmountain.com Q2 2021 Supplemental Financial Information 19

Quarterly Storage Rental and Service Business Detail Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Storage Rental Business Detail Total Storage Rental Revenue $718,272 $708,056 1.4 % $676,956 6.1 % Plus: Terminations/Permanent Withdrawal Fees 6,926 6,953 (0.4) % 4,585 51.1 % Total Revenue from Adjusted Storage Rental Activities $725,198 $715,008 1.4 % $681,541 6.4 % Less: Storage Rental Expenses Storage Rent 99,727 97,289 2.5 % 88,128 13.2 % Other Facility Costs 86,711 87,949 (1.4) % 76,415 13.5 % Storage Rental Labor 7,559 7,253 4.2 % 5,879 28.6 % Other Storage Rental Expenses 11,883 10,847 9.6 % 9,756 21.8 % Storage Rental Cost of Sales $205,880 $203,338 1.3 % $180,178 14.3 % Storage Rental Gross Profit $519,319 $511,670 1.5 % $501,363 3.6 % Storage Rental Gross Margin 71.6 % 71.6 % 0 bps 73.6 % (200 bps) Storage Rental Allocated Overhead 36,908 40,300 (8.4) % 43,616 (15.4) % Total Storage Rental Adjusted EBITDA $482,411 $471,370 2.3 % $457,747 5.4 % Storage Rent 99,727 97,289 2.5 % 88,128 13.2 % Storage Rental Net Operating Income $582,138 $568,659 2.4 % $545,875 6.6 % Service Business Detail Total Service Revenue $401,484 $373,984 7.4 % $305,283 31.5 % Less: Terminations/Permanent Withdrawal Fees 6,926 6,953 (0.4) % 4,585 51.1 % Total Revenue from Adjusted Service Activities $394,559 $367,031 7.5 % $300,698 31.2 % Less: Service Expenses Service Rent 2,868 3,185 (10.0) % 2,816 1.8 % Other Facility Costs 6,792 6,459 5.2 % 6,258 8.5 % Service Labor 191,524 182,143 5.2 % 158,792 20.6 % Other Service Expenses 67,514 56,783 18.9 % 51,000 32.4 % Service Cost of Sales $268,699 $248,571 8.1 % $218,866 22.8 % Service Gross Profit $125,860 $118,461 6.2 % $81,832 53.8 % Service Gross Margin 31.9 % 32.3 % (40 bps) 27.2 % 470 bps Service Allocated Overhead 22,489 26,054 (13.7) % 22,455 0.2 % Total Service Adjusted EBITDA $103,370 $92,407 11.9 % $59,377 74.1 % Section VI - Storage and Service Reconciliation investors.ironmountain.com Q2 2021 Supplemental Financial Information 20

Year to Date Storage Rental And Service Business Detail YTD 2021 YTD 2020 % Change Storage Rental Business Detail Total Storage Rental Revenue $1,426,328 $1,360,503 4.8 % Plus: Terminations/Permanent Withdrawal Fees 13,878 10,024 38.5 % Total Revenue from Adjusted Storage Rental Activities $1,440,207 $1,370,527 5.1 % Less: Storage Rental Expenses Storage Rent $197,016 $178,879 10.1 % Other Facility Costs 174,660 160,834 8.6 % Storage Rental Labor 14,812 11,699 26.6 % Other Storage Rental Expenses 22,730 21,157 7.4 % Storage Rental Cost of Sales $409,218 $372,569 9.8 % Storage Rental Gross Profit $1,030,989 $997,958 3.3 % Storage Rental Gross Margin 71.6 % 72.8 % (120 bps) Storage Rental Allocated Overhead 77,208 81,698 (5.5) % Total Storage Rental Adjusted EBITDA $953,781 $916,260 4.1 % Storage Rent 197,016 178,879 10.1 % Storage Rental Net Operating Income $1,150,796 $1,095,139 5.1 % Service Business Detail Total Service Revenue $775,468 $690,467 12.3 % Less: Terminations/Permanent Withdrawal Fees 13,878 10,024 38.5 % Total Revenue from Adjusted Service Activities $761,590 $680,444 11.9 % Less: Service Expenses Service Rent $6,054 $6,120 (1.1) % Other Facility Costs 13,251 12,317 7.6 % Service Labor 373,667 356,818 4.7 % Other Service Expenses 124,297 118,142 5.2 % Service Cost of Sales $517,270 $493,397 4.8 % Service Gross Profit $244,320 $187,047 30.6 % Service Gross Margin 32.1 % 27.5 % 460 bps Service Allocated Overhead 48,543 47,296 2.6 % Total Service Adjusted EBITDA $195,777 $139,750 40.1 % Section VI - Storage and Service Reconciliation investors.ironmountain.com Q2 2021 Supplemental Financial Information 21

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 3/31/2021 (3) 280 25,796 1,153 66,710 1,433 92,506 Additions & Expansions — — 40 2,677 40 2,677 Dispositions & Move Outs (11) (1,102) (10) (340) (21) (1,442) Total as of 6/30/2021 (4) 269 24,694 1,183 69,047 1,452 93,741 Total % 18.5 % 26.3 % 81.5 % 73.7 % Top Five Markets Owned, United States (in Sq. Ft.) Top Five Markets Owned, International (in Sq. Ft.) Northern New Jersey 1,966 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) 5.2% 5.0% 4.1% 3.9% 5.1% 2.1% 3.3% 3.5% 5.7% 4.9% 57.4% 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Thereafter Weighted-Average Remaining Operating Lease Obligation: 11.5 Years (1) Includes real estate held in consolidated joint ventures. (2) Out of the 40 leased building additions and expansions, 24 were the result of acquiring leases in business acquisitions and leased buildings related to acquisitions of customer relationships. (3) Reflects adjustments to previous periods due to refinements to real estate basis. (4) Includes 10 owned data center facilities and 5 leased data center facilities with 2.5M Sq.Ft. and 0.6M Sq. Ft., respectively. (5) Includes financing and operating lease obligations. Section VII - Real Estate Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 22

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 2021 231 8.0 5.7% $25,060 8.4% 2022 527 20.3 14.3% 56,405 18.8% 2023 297 18.1 12.7% 52,470 17.5% 2024 183 10.9 7.7% 27,433 9.2% 2025 56 13.4 9.4% 33,566 11.2% 2026 44 13.1 9.2% 24,413 8.1% 2027 5 3.2 2.3% 4,107 1.4% Thereafter 22 55.0 38.8% 76,295 25.5% Total 1,365 141.9 100.0% $299,750 100.0% WALE: 3.9 years Data Center Leasing Activity Summary Q2 2021 YTD 2021 Transaction Count GAAP MRR kW $ / kW / Month Transaction Count GAAP MRR kW $ / kW / Month New/expansion leases signed 59 $534 3,610 $148 106 $1,683 12,645 $133 Commenced leases 61 916 5,041 182 102 1,165 6,587 177 Renewed leases 117 1,049 3,947 266 223 2,056 7,778 264 Churn 1.9% 4.2% Cash Mark to Market 2.1% (0.1)% GAAP Mark to Market 2.6% 0.7% LON-2 Data Center Rendering (London, UK) Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 23

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 77.2 % — — 14.2 77.2 % Phoenix AZP-1 41.0 92.9 % — — 41.0 92.9 % AZP-2 4.0 100.0 % — — 4.0 100.0 % AZS-1 5.7 78.2 % — — 5.7 78.2 % Total Phoenix 50.7 91.8 % — — 50.7 91.8 % Denver DEN-1 11.3 83.8 % — — 11.3 83.8 % New Jersey NJE-1 15.1 100.0 % 1.2 — 16.3 92.6 % Northern Virginia VA-1 12.4 66.4 % — — 12.4 66.4 % VA-2 4.0 100.0 % 6.0 50.0 % 10.0 70.0 % Amsterdam AMS-1 12.7 87.0 % 1.1 — 13.8 80.0 % London LON-1 5.1 94.8 % 4.0 — 9.1 52.9 % Singapore SIN-1 6.9 100.0 % — — 6.9 100.0 % Total Data Center Properties 132.4 88.4 % 12.3 24.4 % 144.7 83.0 % Total Potential Capacity - Megawatts Q2 2021 Q2 2020 Leasable 144.7 122.3 Under Construction 66.0 28.7 Held for Development 234.8 207.0 Total Data Center Portfolio 445.5 358.0 Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 24

Data Center Expansion and Development Activity Project / Facilities MW Under Construction MW Pre- leased % Pre- Leased Investment in Q2 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 — — $0.8 $4.8 $45.0 Q4 2022 Q4 2023 4.6 Phoenix AZP-2 Phase 2 12.0 12.0 100.0% $35.8 $48.7 $73.0 Q3 2021 Q3 2021 — AZP-2 Phase 3 2.0 2.0 100.0% — — $7.7 Q3 2021 Q3 2021 — AZP-2 Phase 4 4.0 4.0 100.0% $3.3 $3.3 $26.6 Q4 2021 Q4 2021 — AZP-2 Phase 5 7.0 1.0 14.3% $5.0 $5.0 $100.0 Q3 2022 Q4 2022 19.0 All Other Facilities 43.6 Total Expansion 30.0 19.0 63.3% $44.7 $61.7 $252.3 67.2 New Development Amsterdam AMS-2 — — — — — — 10.6 Chicago CHI-2 — — — — — — 36.0 Frankfurt (1) FRA-1 Phase 1 9.0 9.0 100.0% — — — Q3 2021 Q3 2021 — FRA-1 Phase 2 18.0 18.0 100.0% — — — Q3 2022 Q3 2022 — London LON-2 9.0 — — $0.6 $6.2 $70.7 Q4 2022 Q4 2023 18.0 Northern Virginia VA Future Phases — — — — — — 103.0 Total New Development 36.0 27.0 75.0% $0.6 $6.2 $70.7 167.7 Total Development 66.0 46.0 69.7% $45.3 $67.9 $323.0 234.8 (1) FRA-1 is an unconsolidated joint venture; construction costs are funded by the Joint Venture with Iron Mountain managing the construction. Section VIII - Data Center Customer and Portfolio Metrics investors.ironmountain.com Q2 2021 Supplemental Financial Information 25

Capitalization Senior Credit Facility Capacity $1,959,375 Outstanding $209,375 Letters of Credit $3,238 Remaining Capacity $1,746,762 Interest Rate Spread (Prime) 0.75 % Interest Rate Spread (LIBOR) 1.75 % Weighted Average Interest Rate 1.86 % Maturity Date 6/3/2023 Net Lease-Adjusted Leverage Ratio 5.3x Total Market Capitalization as of 6/30/2021 # of Shares Outstanding 289,459 Share Price as of 06/30/21 $42.32 Total Market Capitalization $12,249,905 Net Debt (1) $8,637,611 Total Enterprise Value $20,887,516 Net Debt to Total Enterprise Value 41.4 % Adjusted EBITDA to Interest Expense 3.9x Credit Facility Fixed Charge Coverage Ratio 2.3x Bond Fixed Charge Coverage Ratio 3.2x Total Enterprise Value to Adjusted EBITDA (2) 13.6x Fixed vs. Floating Rate Debt 86% 14% Fixed Rate Debt Floating Rate Debt Credit Rating S&P Moody's Corporate BB- Ba3 Senior Credit Facility BB Ba3 Outlook Negative Stable Latest Update 5/24/2021 7/2/2021 Total Debt Weighted Average Rates Weighted Average Interest 4.6 % Weighted Average Maturity 7.1 Years USD denominated 81.4 % Debt Maturity Profile ($ in Millions) (3) $42 $470 $488 $16 $560 $696 $1,000 $1,325 $1,000 $1,300 $1,100 $600 Senior Secured Credit Facility Bi-Lateral Loans AUD Term Loan B A/R Securitization USD Term Loan B Mortgage Securitization Senior Unsecured Notes 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 (1) Net debt is calculated as current portion of long-term debt of $106.3M plus long-term debt net of current portion of $8,760.7M plus deferred financing costs of $86.5M less cash and cash equivalents of $315.9M. (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 Q2 2021 Supplemental Financial Information 26

Quarterly Capital Expenditures Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Growth: Data Center 77,556 58,891 31.7 % 54,879 41.3 % Real Estate 19,808 19,717 0.5 % 11,192 77.0 % Innovation and Other 2,894 6,250 (53.7) % 2,410 20.1 % Total Growth Capital Expenditures $100,257 $84,858 18.1 % $68,481 46.4 % Recurring: Real Estate $16,588 $13,225 25.4 % $9,860 68.2 % Non-Real Estate 17,390 14,266 21.9 % 11,711 48.5 % Data Center 1,931 1,092 76.8 % 2,798 (31.0) % Total Recurring Capital Expenditures $35,909 $28,583 25.6 % $24,369 47.4 % Total Growth and Recurring Capital Expenditures $136,166 $113,441 20.0 % $92,850 46.7 % Net Change in Prepaid and Accrued Capital Expenditures 13,892 32,087 (56.7) % 10,164 36.7 % Total Cash Paid for Growth and Recurring Capital Expenditures $150,058 $145,528 3.1 % $103,014 45.7 % Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 27

Year to Date Capital Expenditures YTD 2021 YTD 2020 % Change Growth: Data Center $136,446 $91,831 48.6 % Real Estate 39,525 28,624 38.1 % Innovation and Other 9,144 2,508 264.7 % Total Growth Capital Expenditures $185,115 $122,963 50.5 % Recurring: Real Estate $29,813 $17,295 72.4 % Non-Real Estate 31,656 22,570 40.3 % Data Center 3,023 4,247 (28.8) % Total Recurring Capital Expenditures $64,492 $44,112 46.2 % Total Growth and Recurring Capital Expenditures $249,607 $167,075 49.4 % Net Change in Prepaid and Accrued Capital Expenditures 45,979 33,083 39.0 % Total Cash Paid for Growth and Recurring Capital Expenditures $295,586 $200,158 47.7 % TTM Recurring Capex as a % of Revenue (excl. Data Center) 3.1% 3.1% 3.3% 3.5% 3.7% Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 TTM Data Center Recurring CapEx as a % of Data Center Revenue 3.5% 4.5% 5.7% 5.5% 5.0% Q2 2020 Q3 2020 Q4 2020 Q1 2021 Q2 2021 Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 28

Quarterly Business Acquisitions Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Business Acquisitions Business Acquisitions $49,993 — — — — Change in Business Acquisition Accruals and Cash Acquired (14,270) — — 443 (3,321.2) % Total Cash Paid for Acquisitions, Net of Cash Acquired $35,723 — — $443 7,963.9 % Year to Date Business Acquisitions YTD 2021 YTD 2020 % Change Business Acquisitions Business Acquisitions $49,993 $118,496 (57.8) % Change in Business Acquisition Accruals and Cash Acquired (14,270) 16 (89,287.5) % Total Cash Paid for Acquisitions, Net of Cash Acquired $35,723 $118,512 (69.9) % Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 29

Quarterly Customer Acquisitions Q2 2021 Q1 2021 Q/Q % Change Q2 2020 Y/Y % Change Customer Acquisitions Acquisition of Customer Relationships $2,053 — — $1,151 78.4 % Customer Inducements 2,361 1,457 62.0 % 2,642 (10.6) % Contract Fulfillment Costs 12,304 16,719 (26.4) % 7,596 62.0 % Total Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $16,718 $18,176 (8.0) % $11,389 46.8 % Change in Customer Acquisition Accruals 714 874 (18.3) % — — Total Cash Paid for Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $17,432 $19,050 (8.5) % $11,389 53.1 % Year to Date Customer Acquisitions YTD 2021 YTD 2020 % Change Customer Acquisitions Acquisition of Customer Relationships $2,053 $2,885 (28.8) % Customer Inducements 3,818 6,970 (45.2) % Contract Fulfillment Costs 29,023 18,738 54.9 % Total Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $34,894 $28,593 22.0 % Change in Customer Acquisition Accruals 1,588 — — Total Cash Paid for Acquisition of Customer Relationships, Customer Inducements, and Contract Fulfillment Costs $36,482 $28,593 27.6 % Section X - Capital Expenditures and Acquisitions investors.ironmountain.com Q2 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, (loss) income 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 expense (income), 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 expense (income), 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. 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): 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) Loss (gain) on disposal/write-down of property, plant and equipment, net (excluding real estate); (v) Other expense (income), 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. 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. Section XI - Appendix and Definitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 31

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 58 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, and (v) on-demand, valet storage for consumers (“Consumer Storage”) across 31 markets in North America through a strategic partnership (the “MakeSpace JV”) with MakeSpace Labs, Inc., a consumer storage provider (“MakeSpace”), formed in March 2019. The MakeSpace JV 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. The world’s most heavily regulated organizations have trusted us with their data centers for over 15 years, and five of the top 10 global cloud providers were Iron Mountain Data Center customers. 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 four international markets: Amsterdam, London, Singapore and, through an unconsolidated joint venture, Frankfurt. 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. 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. During 2020, a portion of what was previously categorized as Non-Real Estate Growth Capital Expenditures was recategorized as Real Estate Growth Capital Expenditures and the remaining portion was recategorized as Recurring Capital Expenditures. In addition, capital expenditures associated with restructuring (including Project Summit) and integration of acquisitions, which was previously categorized as recurring capital expenditures, have been recategorized as Innovation and Other. We have reclassified the categorization of our prior year capital expenditures to conform with our current presentation. Section XI - Appendix and Definitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 32

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: - is 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: - The Credit Facility Fixed Charge Coverage Ratio is 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: - The calculation for this ratio is 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. Significant Acquisition Capital Expenditures: – Represents capitalized expenditures associated with the May 2, 2016 acquisition of Recall Holdings Limited ("Recall") pursuant to the Scheme Implementation Deed, as amended with Recall (the "Recall Transaction") and the acquisition of IO Data Centers, LLC. Service Profit and Margin: – The Gross Profit and Margin attributable to the worldwide service business. Calculated as follows: Services Adjusted EBITDA + Allocated Overhead Expenses + Termination and Permanent Withdrawal Fees = Service Profit ($) / Total Service Revenues (including Termination and Permanent Withdrawal Fees) = Service 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. Section XI - Appendix and Definitions investors.ironmountain.com Q2 2021 Supplemental Financial Information 33

Storage Profit and Margin: – The Gross Profit and Margin attributable to the worldwide storage business. Calculated as follows: Storage Net Operating Income + Allocated Overhead Expenses - Storage Rent - Termination and Permanent Withdrawal Fees = 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: - Comprised of 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 Q2 2021 Supplemental Financial Information 34