Item 1. BUSINESS.

BUSINESS OVERVIEW

We help organizations around the world protect their information, reduce storage costs, comply with regulations, facilitate corporate disaster recovery and better use their information and IT infrastructure for business advantages, regardless of its format, location or life cycle stage. We do this by storing physical records and data backup media, offering information management solutions and providing data center space for enterprise-class colocation and hyperscale deployments. We offer comprehensive records and information management services and data management services, along with the expertise and experience to address complex storage and information management challenges such as rising storage rental costs, legal and regulatory compliance and disaster recovery requirements. We provide secure and reliable data center facilities to protect digital information and ensure the continued operation of our customers’ IT infrastructure, with reliable and flexible deployment options. Our asset lifecycle management ("ALM") business allows us to provide end-to-end asset lifecycle services for hyperscale, corporate data center and corporate end-user device assets.

Founded in an underground facility near Hudson, New York in 1951, Iron Mountain Incorporated, a Delaware corporation ("IMI"), has more than 225,000 customers in a variety of industries in 60 countries around the world, as of December 31, 2023. We currently serve customers across an array of market verticals - commercial, legal, financial, healthcare, insurance, life sciences, energy, business services, entertainment and government organizations, including more than 90% of the Fortune 1000. As of December 31, 2023, we employed approximately 27,000 people. We are listed on the New York Stock Exchange (the "NYSE") and are a constituent of the Standard & Poor’s 500 Index and the Morgan Stanley Capital International ("MSCI") REIT index. As of December 31, 2023, we were number 641 on the Fortune 1000.

We have been organized and have operated as a REIT beginning with our taxable year ended December 31, 2014.

BUSINESS STRATEGY

OVERVIEW

Our company has been a market leader in the physical ecosystem supporting information storage and retrieval, as most businesses have relied on paper documents or computer tapes to store their valuable information. Over time, customers are increasing their digital information, with the new information storage ecosystem being a hybrid of physical and digital media. We are a different company to the one we have been in our past. The strategic journey we are on is driving this change and our focus remains on the four pillars outlined below to continue to grow and evolve our business.

Continued revenue growth in physical storage through revenue management actions as well as volume growth achieved in faster growing markets and our consumer business, as well as complementary business growth			•We are establishing and enhancing leadership positions in higher-growth markets such as central and eastern Europe, Latin America, Asia, the Middle East and Africa. •We continue to identify, acquire, incubate and scale complementary businesses and products to support our long-term growth objectives and drive solid returns on invested capital. These opportunities include our digital services and our ALM, Entertainment Services, Fine Arts and Consumer Storage (each as defined below) businesses.
Utilizing our global scale as well as over 70 years of customer trust to deliver differentiated data center offerings			•We have made significant progress in scaling our Global Data Center Business through acquisitions and organic growth, with 26 operating data centers across 21 global markets, either directly or through unconsolidated joint ventures. •As of December 31, 2023, approximately 93% of our data center capacity was leased. With total potential capacity of 861 megawatts ("MW") in land and buildings currently owned or operated by us, we are among the largest global data center operators.

			IRON MOUNTAIN 2023 FORM 10-K			1

Part I

Establishing and maintaining a leadership position in critical digital infrastructure as well as developing and offering new products and services that allow our customers to achieve reliable and secure information management solutions in an increasingly hybrid physical and digital world			•We are positioned to take advantage of the secular growth trends of the changing nature of digital infrastructure. We continue to scale our digital solutions business to complement our existing offerings in records and information management, in addition to expanding our existing leadership capabilities in our ALM, including enterprise secure IT asset disposition, and data center businesses in order to respond to our customers’ growing interest and need to react to environmental, social and corporate governance considerations. This full suite of complementary businesses puts Iron Mountain in a unique position to cross sell our products and services to our customers. •Our customers are faced with navigating a more complex regulatory environment, and one in which hybrid physical and digital solutions have become the norm. Our strategy is underpinned by our persistent focus on best-in-class customer experience, as we continue to seek innovative solutions to help our customers progress on their journey from physical storage to a digital ecosystem.
Increased investment in our growth agenda, our business and customer-centric solutions			•We have established an investment strategy to fuel our growth. The investments we outlined in our plan for Project Matterhorn (as defined below) have been informed by our established leadership position in the physical storage business, our expanding services such as Global Digital Solutions and ALM and our significant progress in the Global Data Center Business.

PROJECT MATTERHORN

In September 2022, we announced a global program designed to accelerate the growth of our business ("Project Matterhorn"). Project Matterhorn investments focus on transforming our operating model to a global operating model. Project Matterhorn focuses on the formation of a solution-based sales approach that is designed to allow us to optimize our shared services and best practices to better serve our customers' needs. We are investing to accelerate growth and to capture a greater share of the large, global addressable markets in which we operate. We expect to incur approximately $150.0 million in costs annually related to Project Matterhorn from 2023 through 2025. Costs are comprised of (1) restructuring costs, which include (i) site consolidation and other related exit costs, (ii) employee severance costs and (iii) certain professional fees associated with these activities and (2) other transformation costs, which include professional fees such as project management costs and costs for third party consultants who are assisting in the enablement our growth initiatives. Total costs related to Project Matterhorn during the years ended December 31, 2023 and 2022 were approximately $175.2 million and $41.9 million, respectively.

BUSINESS SEGMENTS

The amount of revenues derived from our business segments and other relevant data, including financial information about geographic areas and product and service lines, for the years ended December 31, 2023, 2022 and 2021, are set forth in Note 11 to Notes to Consolidated Financial Statements included in this Annual Report.

GLOBAL RIM BUSINESS

The Global Records and Information Management ("Global RIM") Business segment includes several distinct offerings.

Records Management, stores physical records and provides information services, vital records services, courier operations, and the collection, handling and disposal of sensitive documents ("Records Management") for customers in 60 countries around the globe. As of December 31, 2023, we stored approximately 731.5 million cubic feet of hardcopy records.

Data Management, provides storage and rotation of backup computer media as part of corporate disaster recovery plans, including service and courier operations, server and computer backup services and related services offerings ("Data Management").

Global Digital Solutions, develops, implements and supports comprehensive storage and information management solutions for the complete lifecycle of our customers’ information, including the management of physical records, conversion of documents to digital formats and digital storage of information ("Global Digital Solutions").

Secure Shredding, includes the scheduled pick-up of office records that customers accumulate in specially designed secure containers we provide and is a natural extension of our hardcopy records management operations, completing the lifecycle of a record. Through a combination of shredding facilities and mobile shredding units consisting of custom built trucks, we are able to offer secure shredding services to our customers.

Entertainment Services, entertainment and media services which help industry clients store, safeguard and deliver physical media of all types, and provides digital content repository systems that house, distribute, and archive key media assets ("Entertainment Services").

2			IRON MOUNTAIN 2023 FORM 10-K

Part I

Consumer Storage, provides on-demand, valet storage for consumers ("Consumer Storage") utilizing data analytics and machine learning to provide effective customer acquisition and a convenient and seamless consumer storage experience.

GLOBAL DATA CENTER BUSINESS

The Global Data Center Business segment 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 as of December 31, 2023, five of the top 10 global cloud providers were Iron Mountain Data Center customers.

CORPORATE AND OTHER

Corporate and Other consists primarily of our Fine Arts and ALM businesses and other corporate items ("Corporate and Other").

Fine Arts, provides technical expertise in the handling, installation and storing of art ("Fine Arts").

ALM, provides hyperscale and corporate IT infrastructure managers with services and solutions that enable the decommissioning, data erasure, processing and disposition or sale of IT hardware and component assets. ALM services are enabled by: secure logistics, chain of custody and complete asset traceability practices, environmentally-responsible asset processing and recycling, and data sanitization and asset refurbishment services that enable value recovery through asset remarketing. In addition, ALM also offers workplace IT asset management services including storage, configuration, deployment, device support and end-of-life disposition for employee IT devices. Our ALM services focus on protecting and eradicating customer data while maintaining strong, auditable and transparent chain of custody practices.

Corporate and Other also includes costs related to executive and staff functions, including finance, human resources and IT, which benefit the enterprise as a whole.

			IRON MOUNTAIN 2023 FORM 10-K			3

Part I

BUSINESS ATTRIBUTES

Our business has the following attributes:

Large, Diversified, Global Business			The world’s most heavily regulated organizations trust us with the storage of their records. Our mission-critical storage offerings and related services generated approximately $5.5 billion in annual revenue in 2023. Our business has a highly diverse customer base of more than 225,000 customers - with no single customer accounting for more than approximately 1% of revenue during the year ended December 31, 2023 - and operates in 60 countries globally. This presents a significant cross-sell opportunity for our expanding solutions, including digital, data center and ALM.
Recurring, Durable Revenue Stream			We generate a majority of our revenues from contracted storage rental fees, via agreements that generally range from one to five years in length. Historically, in our Records Management business, we have seen strong customer retention (of approximately 98%) and solid physical records retention; more than 50% of physical records that entered our facilities approximately 15 years ago are still with us today. We have also seen strong customer retention in our Global Data Center Business.
Comprehensive Information Management Solution			As an S&P 500 REIT with approximately 1,400 locations globally and with offerings spanning physical storage, digitization solutions and digital storage, we are positioned to provide a holistic offering to our customers. We are able to cater to our customers’ physical and digital needs and to help guide their digital transformation journey.
Significant Owner and Operator of Real Estate			We operate approximately 98 million square feet of real estate worldwide. Our owned real estate footprint spans to over 23 million square feet.
Limited Revenue Cyclicality			Historically, economic downturns have not significantly affected our storage rental business. Due to the durability of our total global physical volumes, the success of our revenue management initiatives, and the growth of our Global Data Center Business, we believe we can continue to grow organic storage rental revenue over time.
Shifting Revenue Mix			We have identified a number of areas where we see opportunity for growth as we position ourselves to unlock greater value for our customers. These business lines, including Global Data Center, ALM and Consumer Storage, represent markets with strong secular growth.

4			IRON MOUNTAIN 2023 FORM 10-K

Part I

In addition, our Global Data Center Business has the following attributes:

Large Data Center Platform with Significant Expansion Opportunity			As of December 31, 2023, we had 250 MW of leasable capacity with an additional 611 MW under construction or held for development.
Differentiated Compliance and Security			We offer comprehensive compliance support and physical and cyber security. Our Security-in-Depth approach to security includes a combination of technical and human security measures, and experienced senior military and public sector security leaders oversee our security. As of December 31, 2023, our data centers comply with one of the most comprehensive compliance programs in the industry, including enterprise-wide certified ISO 14001 and 50001 environmental and energy management systems. We also report globally on service organizational controls, as well as global ISO 27001 certification, and PCI-DSS compliance, and meet FISMA HIGH and FedRAMP controls in the United States.
Efficient Access and Flexibility			We have the ability to provide customers with a range of deployment options from one cabinet to an entire building, leveraging our global portfolio of hyperscale-ready and underground data centers. We also provide access to numerous carriers, cloud providers and peering exchanges with migration support.
100% Green Powered Data Centers			As of December 31, 2023, our Global Data Center platform continues to match 100% of its consumption with renewable electricity procurement and benefits from low power usage effectiveness ("PUE"). As of October 2023, we are in the top 30 of the Environmental Protection Agency's National Top 100 Partners list, with green power comprising 94% of our company-wide U.S. electricity use. We offer the Green Power Pass, which allows customers to include the power they consume at any Iron Mountain data centers as green power in their CDP, RE100, GRI or other sustainability reporting.

COMPETITION

We compete with thousands of storage and information management services providers around the world, as well as storage and information management services managed and operated internally by organizations. We believe that competition for records and information customers is based on price, reputation and reliability, quality and security of storage, quality of service and scope and scale of technology. While the majority of our competitors operate in only one market or region, we believe we provide a differentiated global offering that competes effectively in these areas.

We also compete with numerous data center developers, owners and operators, many of whom own properties similar to ours in some of the same metropolitan areas where our facilities are located. We believe that competition for data center customers is based on availability of power, security considerations, location, connectivity and rental rates, and we generally believe we compete effectively in each of these areas. Additionally, we believe our strong brand, global footprint and excellent commercial relationships enable us to compete successfully and provide significant cross-sell opportunities with our existing customer base.

Similarly, in our ALM business, we compete with both hyperscalers and individual corporate clients who manage their own asset recycling and management, as well as external competitors.

HUMAN CAPITAL MANAGEMENT

EMPLOYEES

As of December 31, 2023, we employed approximately 10,500 employees in the United States and approximately 16,500 employees outside of the United States. As of December 31, 2023, approximately 400 employees were represented by unions in North America and approximately 725 employees were represented by unions in Latin America. All union employees are currently under renewed labor agreements or operating under an extension agreement.

			IRON MOUNTAIN 2023 FORM 10-K			5

Part I

BENEFIT PROGRAMS

We provide our employees with benefits that are designed to support their overall physical, financial, emotional and social well-being. These benefits vary by location but generally include health and welfare benefits, paid time off, and programs to support financial security. Additionally, employees are able to access emotional well-being resources through global employee assistance programs. Certain unionized employees receive benefits through unions and are not eligible to participate in our benefit programs. In addition to base compensation and other usual benefits, a significant portion of full-time employees participate in some form of incentive-based compensation program that provides payments based on revenues, profits or attainment of specific objectives for the unit in which they work.

COMPANY CULTURE

We recognize that an inspired culture is foundational to how we deliver on our purpose and create sustained growth and value for our shareholders. Iron Mountain's culture is deeply rooted in its enduring values: Act with Integrity, Own Safety and Security, Build Customer Value, Take Ownership and Promote Inclusion and Teamwork. While Iron Mountain is a culture of learning, collaboration, diversity and well-being, we know that culture overall comes down to what it feels like to work at Iron Mountain. This is why we celebrate and recognize our employees who consistently demonstrate Iron Mountain's values in measurable ways while inspiring others to do the same. We commit significant resources to sustaining a culture that enables voice and innovation, and facilitates trust, engagement, belonging and performance. We regularly survey our employees on a range of topics to measure our engagement and effectiveness and to obtain their views. In addition, we use data to gain insight to the global distribution of our employees, where they work, how they work and cost to serve. We use all of this information to drive increased employee engagement and success, as well as to refine our approach.

DIVERSITY, EQUITY AND INCLUSION

We continue to prioritize diversity, equity, and inclusion ("DEI") as core principles of our corporate strategic goals.

Our Global DEI Council is made up of the Executive Leadership Team and is chaired by Iron Mountain President and CEO Bill Meaney. The Global DEI Council supports our DEI strategy and initiatives, monitors the progress of DEI initiatives and enterprise goals, ensures accountability based on identifiable measures and goals and communicates DEI progress to stakeholders.

In June 2023, we committed to investing in the growth and wellbeing of our female leaders (Directors and VPs) by funding a comprehensive development program, Women in Leadership ("WiL"). WiL is specifically designed to support women in their career progression and prepare them for critical leadership roles.

We also formally expanded our investment in our Employee Resource Groups ("ERGs") to elevate their impact and reach. Our ERGs support Iron Mountain’s DEI strategy by fostering a sense of belonging for their colleagues, increasing talent attraction, retention, and development efforts and being supportive partners.

Iron Mountain scored 90% on the Human Rights Campaign’s Corporate Equality Index for LGBTQ+ and placed as a top scorer on the 2023 Disability Equality Index. We also received the JPMorgan Chase Strategic Diverse Gold Supplier Award for our commitment to supplier diversity, and the contributions of our very own supplier diversity program where we exceeded our target of $70 million in supplier diversity spend during fiscal 2023. In July 2023, Bill Meaney was named among the best CEOs for diversity in a large company by Comparably, a ZoomInfo Technologies company that collects data on wage equity and company culture. In addition, Iron Mountain was named among Comparably's 2023 Best Companies for Women and Best Companies for Diversity.

COMMUNITY INVOLVEMENT

We are committed to integrating responsible and sustainable practices throughout our organization to help our operations have a positive impact on the environment and the communities in which we operate. We aim to give back to the communities where we live and work, and believe that this commitment helps in our efforts to attract and retain employees. We offer philanthropic support to our global community through our Living Legacy Initiative, which is our commitment to help preserve and make accessible cultural and historical information and artifacts. We encourage volunteerism in the communities in which we live and work through our Moving Mountains volunteer program, offering paid time off for employees to help community-based and civic-minded organizations.

6			IRON MOUNTAIN 2023 FORM 10-K

Part I

INSURANCE

For strategic risk transfer purposes, we maintain a comprehensive insurance program with insurers that we believe to be reputable and which have adequate capitalization in amounts that we believe to be appropriate. Property insurance is purchased on a comprehensive basis, including flood and earthquake (including excess coverage), subject to certain policy conditions, sublimits and deductibles. Property is insured based upon the replacement cost of real and personal property, including leasehold improvements, business income loss and extra expense. Other types of insurance that we carry, which are also subject to certain policy conditions, sublimits and deductibles, include medical, workers’ compensation, general liability, umbrella, automobile, professional, cyber, warehouse legal liability and directors’ and officers’ liability policies.

GOVERNMENT REGULATION

We are required to comply with numerous laws and regulations covering a wide variety of subject matters which may have a material effect on our capital expenditures, earnings and competitive position.

For example, some of our currently and formerly owned or leased properties were previously used by entities other than us for industrial or other purposes, or were affected by waste generated from nearby properties, that involved the use, storage, generation and/or disposal of hazardous substances and wastes, including petroleum products. In some instances, this prior use involved the operation of underground storage tanks or the presence of asbestos-containing materials. Where we are aware of environmental conditions that require remediation, we undertake appropriate activity, in accordance with all legal requirements. Although we have from time to time conducted limited environmental investigations and remedial activities at some of our former and current facilities, we have not undertaken environmental reviews of all of our properties. We therefore may be potentially liable for environmental costs and may be unable to sell, rent, mortgage or use contaminated real estate owned or leased by us. Under various federal, state and local environmental laws, we may be liable for environmental compliance and remediation costs to address contamination, if any, located at owned and leased properties as well as damages arising from such contamination, whether or not we know of, or were responsible for, the contamination, or the contamination occurred while we owned or leased the property. Environmental conditions for which we might be liable may also exist at properties that we may acquire in the future. In addition, future regulatory action and environmental laws may impose costs for environmental compliance that do not exist today.

We transfer a portion of our risk of financial loss due to currently undetected environmental matters by purchasing an environmental impairment liability insurance policy, which covers all owned and leased locations. Coverage is provided for both liability and remediation costs.

In addition, we are subject to numerous laws and regulations relating to data privacy and cybersecurity, which are complex, change frequently and have tended to become more stringent over time. We have an established privacy compliance framework and devote substantial resources, and may in the future have to devote significant additional resources, to facilitate compliance with these laws and regulations, and to investigate, defend or remedy actual or alleged violations or breaches. Any failure by us to comply with, or remedy any violations or breaches of, these laws and regulations could negatively impact our operations, result in the imposition of fines and penalties, liability and litigation, significant costs and expenses and reputational harm.

For more information about laws and regulations that could affect our business, see "Item 1A. Risk Factors" included in this Annual Report.

SUSTAINABILITY

At Iron Mountain, we are using our influence and expertise to drive innovations that will not only protect and elevate the power of our customers’ work, but make a lasting, positive impact on people, planet, and performance. Our four focus areas, where we can deliver uniquely through owned operations and customers' enablement, are safeguarding our customers’ information, empowering employees, serving our communities, and protecting the environment.

Iron Mountain is committed to sustainable growth, and this is highlighted through initiatives and targets within the company. We have successfully achieved seven of the ambitious sustainability goals we set in 2021 to address our environmental footprint, corporate philanthropy, volunteerism and DEI practices. We are committed to reach net zero greenhouse gas emissions by 2040. As an employer, we are committed to the safety and well-being of our employees and strive to cultivate a culture of inclusion that values diverse perspectives across our global workforce. Iron Mountain and its employees also make a social impact in the communities in which we operate through charitable giving and volunteerism.

Our work continues to receive recognition. In 2023, Iron Mountain received the Low Carbon Hero Award recognizing our efforts to implement social and technical practices to reduce our carbon footprint. Also in 2023, Iron Mountain joined EV100 and is committed to electrifying 100% of our company cars and 50% of our vans by 2030. With operations in 60 countries, Iron Mountain was recognized as the most international committed fleet in the 2023 EV100 Annual Report.

			IRON MOUNTAIN 2023 FORM 10-K			7

Part I

Iron Mountain is committed to transparent reporting on our sustainability efforts and we leverage widely adopted reporting frameworks to report annually on our results. Our annual sustainability report, aligned with the Global Reporting Initiative framework, highlights our progress against key measures of success for our community, environment and people. In addition, we continue to work to further align our reporting with the recommendations of the Financial Stability Board’s Task Force on Climate-related Financial Disclosures to disclose climate-related financial risks and opportunities, and in 2022 we completed our first climate scenario analysis. The process brought together our most senior leaders from across all business units and functions to explore the potential impacts of climate change related to several different warming scenarios. The analysis resulted in the identification of seven strategic themes where Iron Mountain should focus its future discussions regarding climate resilience, which include physical impacts, business strategy and innovation, and reputational and societal risks.

We are a member of the FTSE4Good Index, MSCI World ESG Index, MSCI World Climate Change Index and MSCI USA ESG Select Index, each of which include companies that meet globally recognized corporate responsibility standards. A copy of our sustainability responsibility report is available on the "Who we are" section of our website, www.ironmountain.com, under the heading "Sustainability". We are not including the information contained on or available through our website as part of, or incorporating such information by reference into, this Annual Report.

STRONG ENVIRONMENTAL FOCUS •Iron Mountain provides a Green Power Pass solution in the Data Center market to help customers manage their carbon footprint. •A part of RE100 and EV100 Initiatives - commitment to use renewable energy sources for 100% of our worldwide electricity by 2040 and convert 100% of our company cars and 50% of our vans to electric vehicles by 2030. •Founding signatory of the 24/7 Carbon Free Energy (CFE) compact. As of 2023, Iron Mountain has over 130 locations across the United States with the ability to track and match renewable energy usage on an hourly basis. •85% of our global electricity use was from renewable sources in 2022. •Reduced Scope 1 and 2 greenhouse gas (GHG) emissions by 32% compared to our 2016 baseline as part of our net zero by 2040 commitment. •Received 90% or greater on the Human Rights Campaign Corporate Equality Index every year since 2018.

INTERNET WEBSITE

Our Internet address is www.ironmountain.com. Under the "Investors" section on our website, we make available, free of charge, our Annual Reports on Form 10-K, our Quarterly Reports on Form 10-Q, our Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (the "Exchange Act") as soon as reasonably practicable after such forms are filed with or furnished to the SEC. We are not including the information contained on or available through our website as a part of, or incorporating such information by reference into, this Annual Report. Copies of our corporate governance guidelines, code of ethics and the charters of our audit, compensation, finance, nominating and governance, risk and safety, and technology committees are available on the "Investors" section of our website, www.ironmountain.com, under the heading "Corporate Governance".

8			IRON MOUNTAIN 2023 FORM 10-K

Part I