(AMT)

Role: EVP, Chief Admin Ofr, GC & Sec
Signature: /s/ Marina A. Breed, as attorney-in-fact
Issuer symbol: AMT
Transactions as of: 25 Feb 2026
Net transactions value: $0
Form type: 4
Filing time: 27 Feb 2026, 16:10:04 UTC
Previous filing: 03 Oct 2025
Next filing: 03 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Dowling Ruth T	EVP, Chief Admin Ofr, GC & Sec	222 BERKELEY STREET, BOSTON	/s/ Marina A. Breed, as attorney-in-fact	27 Feb 2026	0001960785

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	AMT	Common Stock	Award	$0	+11,083	+52%	$0.000000	32,385	25 Feb 2026	Direct	F1, F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Reflects the number of performance-based restricted stock units ("PSUs") earned, as a result of the Compensation and Human Capital Committee's certification to the achievement of performance based on a three-year performance period, under the terms of a PSU award granted on March 10, 2023. These shares will vest three years from the grant date of such PSU award, and each PSU represents a contingent right to receive one share of Common Stock.
F2	Includes 40 shares acquired under the issuer's employee stock purchase plan in November 2025.

Content

Reflects the number of performance-based restricted stock units ("PSUs") earned, as a result of the Compensation and Human Capital Committee's certification to the achievement of performance based on a three-year performance period, under the terms of a PSU award granted on March 10, 2023. These shares will vest three years from the grant date of such PSU award, and each PSU represents a contingent right to receive one share of Common Stock.

Includes 40 shares acquired under the issuer's employee stock purchase plan in November 2025.