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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One):

For the fiscal year ended December 31, 2020

For the transition period from to

Commission File Number: 001-14195

American Tower Corporation

(Exact name of registrant as specified in its charter)

116 Huntington Avenue

Boston, Massachusetts 02116

(Address of principal executive offices)

Telephone Number (617) 375-7500

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well known seasoned issuer, as defined in Rule 405 of the Securities Act: Yes ☒ No ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act: Yes ☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days: Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check One):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (§15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act): Yes ☐ No ☒

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the registrant as of June 30, 2020 was $114.3 billion, based on the closing price of the registrant’s common stock as reported on the New York Stock Exchange as of the last business day of the registrant’s most recently completed second quarter.

As of February 18, 2021, there were 444,384,437 shares of common stock outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the definitive proxy statement (the “Definitive Proxy Statement”) to be filed with the Securities and Exchange Commission relative to the registrant’s 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Report.

AMERICAN TOWER CORPORATION

TABLE OF CONTENTS

FORM 10-K ANNUAL REPORT

FISCAL YEAR ENDED DECEMBER 31, 2020

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AMERICAN TOWER CORPORATION

TABLE OF CONTENTS—(Continued)

FORM 10-K ANNUAL REPORT

FISCAL YEAR ENDED DECEMBER 31, 2020

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K (this “Annual Report”) contains statements about future events and expectations, or forward-looking statements, all of which are inherently uncertain. We have based those forward-looking statements on our current expectations and projections about future results. When we use words such as “anticipates,” “intends,” “plans,” “believes,” “estimates,” “expects” or similar expressions, we are making forward-looking statements. Examples of forward-looking statements include, but are not limited to, our expectations regarding the impacts of the coronavirus (“COVID-19”) pandemic and actions in response to the COVID-19 pandemic on our business and our operating results, statements we make regarding the Pending Telxius Acquisition (as defined in this Annual Report), future prospects of growth in the communications site leasing industry, the effects of consolidation among companies in our industry and among our tenants and other competitive and financial pressures, changes in zoning, tax and other laws and regulations and administrative and judicial decisions, economic, political and other events, particularly those relating to our international operations, our future capital expenditure levels, our ability to maintain or increase our market share, our plans to fund our future liquidity needs, our substantial leverage and debt service obligations, our future financing transactions, our future operating results, the level of future expenditures by companies in this industry and other trends in this industry, the impact of technology changes on our industry and our business, our ability to remain qualified for taxation as a real estate investment trust (REIT), the amount and timing of any future distributions including those we are required to make as a REIT, natural disasters and similar events and our ability to protect our rights to the land under our towers. These statements are based on our management’s beliefs and assumptions, which in turn are based on currently available information. These assumptions could prove inaccurate. These forward-looking statements may be found under the captions “Business” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” as well as in this Annual Report generally.

You should keep in mind that any forward-looking statement we make in this Annual Report or elsewhere speaks only as of the date on which we make it. New risks and uncertainties arise from time to time, and it is impossible for us to predict these events or how they may affect us. In any event, these and other important factors, including those set forth in Item 1A of this Annual Report under the caption “Risk Factors,” may cause actual results to differ materially from those indicated by our forward-looking statements. We have no duty, and do not intend, to update or revise the forward-looking statements we make in this Annual Report, except as may be required by law. In light of these risks and uncertainties, you should keep in mind that the future events or circumstances described in any forward-looking statement we make in this Annual Report or elsewhere might

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not occur. References in this Annual Report to “we,” “our” and the “Company” refer to American Tower Corporation and its predecessor, as applicable, individually and collectively with its subsidiaries as the context requires.

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PART I