AMT: Material agreement · New financial obligation

Item 1.01 Entry into a Material Definitive Agreement. On May 27, 2026, American Tower Corporation (the “Company”) completed a registered public offering of 750.0 million euros (“EUR”) aggregate principal amount of its 4.000% senior unsecured notes due 2033 (the “notes”), which resulted in aggregate net proceeds to the Company of approximately 742.7 million EUR (approximately $866.7 million at the EUR/U.S. dollar exchange rate of 1.00 EUR = $1.1669, as reported by Bloomberg on May 14, 2026), after deducting commissions and estimated expenses. The Company intends to use the net proceeds to repay existing indebtedness drawn under its $6.0 billion senior unsecured multicurrency revolving credit facility, as amended and restated in December 2021, as further amended, to the extent it has been drawn upon in EUR to repay 500.0 million EUR aggregate principal amount of the Company’s 1.950% senior notes due 2026, and for general corporate purposes. The Company issued the notes under an indenture dated as of June 2, 2025 (the “Base Indenture”), between the Company and U.S. Bank Trust Company, National Association, as trustee (the “Trustee”), as supplemented by a supplemental indenture dated as of May 27, 2026 (the “Supplemental Indenture No. 2” and, together with the Base Indenture, the “Indenture”), among the Company, the Trustee and U.S. Bank Europe DAC, UK Branch, as paying agent. The following description of the Indenture is a summary and is qualified in its entirety by reference to the detailed provisions of the Indenture. The notes will mature on September 1, 2033 and bear interest at a rate of 4.000% per annum. Accrued and unpaid interest on the notes will be payable in EUR in arrears on September 1 of each year, beginning on September 1, 2026. Interest on the notes will ac