SUPPLEMENTAL INDENTURE NO. 9 (the Supplemental Indenture), dated as of
December 8, 2017, between American Tower Corporation, a Delaware corporation (the Company), and U.S. Bank National Association, a national banking association, as trustee (the Trustee).
WHEREAS, the Company and the Trustee have executed and delivered a base indenture, dated as of May 23, 2013 (the Base
Indenture, and, together with this Supplemental Indenture, as amended, supplemented or otherwise modified from time to time, the Indenture) to provide for the future issuance of the Companys senior debt securities
to be issued from time to time in one or more series;
WHEREAS, pursuant to the terms of the Base Indenture, the Company
desires to provide for the establishment of two series of its Securities, to be titled as its 3.000% Senior Notes due 2023 (the 2023 Notes) and 3.600% Senior Notes due 2028 (the 2028
Notes) the form and substance of such Securities and the terms, provisions and conditions thereof to be set forth as provided in the Indenture; and
WHEREAS, all acts and requirements necessary to make this Supplemental Indenture, when executed and delivered by the parties hereto, the
legal, valid and binding obligation of the Company, in accordance with its terms, have been done.
Each party agrees as follows for the benefit of the other party and for the equal and ratable benefit of the Holders of the Securities.
ARTICLE I DEFINITIONS AND INCORPORATION BY REFERENCE
Section 1.01. DEFINITIONS.
Capitalized terms used herein without definition shall have the respective meanings ascribed to them in the Base Indenture. The following
definitions supplement, and, to the extent inconsistent with, replace the definitions in Article I of the Base Indenture:
Additional Security Board Resolution means resolutions duly adopted by the Board of Directors of the Company and delivered
to the Trustee in an Officers Certificate providing for issuance of Additional Securities.
Supplemental Indenture means a supplement to this Indenture duly executed and delivered by the Company and the Trustee pursuant to Article 7 of the Base Indenture.
Additional Securities means the Companys Securities originally issued hereunder after the Issue Date pursuant to
Section 2.13 hereof, except for Securities authenticated and delivered upon registration of, transfer of, or in exchange for, or in lieu of other Securities pursuant to Section 3.07, 3.09, 7.05 or 9.06 of the Base Indenture, or 4.01(b)
hereof, as specified in the relevant Additional Security Board Resolutions or Additional Security Supplemental Indenture issued therefor in accordance with this Indenture.
Adjusted EBITDA means, for the 12-month period preceding the calculation date, for the Company and its Subsidiaries on a
consolidated basis in accordance with GAAP, the sum of (a) Net Income, plus (b) to the extent deducted in determining Net Income, the sum of (i) Interest Expense, (ii) income tax expense, including, without limitation, taxes paid
or accrued based on income, profits or capital, including state, franchise and similar taxes and foreign withholding taxes, (iii) depreciation and amortization (including, without limitation, amortization of goodwill and other intangible
assets), (iv) extraordinary losses and non-recurring non-cash charges and expenses, (v) all other non-cash charges, expenses and interest (including, without limitation, any non-cash losses in respect of Commodity Agreements, Currency
Agreements or Interest Rate Agreements, non-cash impairment charges, non-cash valuation charges for stock option grants or vesting of restricted stock awards or any other non-cash compensation charges, and losses from the early extinguishment of
Indebtedness) and (vi) non-recurring charges and