(AMT)

Role: EVP, CFO & Treasurer
Signature: /s/ Marina A. Breed, as attorney-in-fact
Issuer symbol: AMT
Transactions as of: 17 Feb 2026
Net transactions value: -$3,344,091
Form type: 4
Filing time: 19 Feb 2026, 16:07:36 UTC
Previous filing: 12 Mar 2025
Next filing: 27 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Smith Rodney M	EVP, CFO & Treasurer	222 BERKELEY STREET, BOSTON	/s/ Marina A. Breed, as attorney-in-fact	19 Feb 2026	0001807541

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	AMT	Common Stock	Options Exercise	$3,252,436	+34,341	+46%	$94.71	108,655	17 Feb 2026	Direct	F1
transaction	AMT	Common Stock	Sale	$397,070	-2,086	-1.9%	$190.35	106,569	17 Feb 2026	Direct	F2, F3
transaction	AMT	Common Stock	Sale	$1,837,826	-9,596	-9%	$191.52	96,973	17 Feb 2026	Direct	F2, F4
transaction	AMT	Common Stock	Sale	$4,361,438	-22,658	-23%	$192.49	74,315	17 Feb 2026	Direct	F2, F5
transaction	AMT	Common Stock	Sale	$193	-1	-0%	$193.13	74,314	17 Feb 2026	Direct	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	AMT	Option to Purchase Common Stock	Options Exercise	$0	-34,341	-100%	$0.000000	0	17 Feb 2026	Common Stock	34,341	$94.71	Direct	F6

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

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id	Content
F1	Includes 93 and 26 shares acquired under the issuer's employee stock purchase plan in May 2025 and in November 2025, respectively.
F2	The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 22, 2025.
F3	Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $189.93 to $190.88 per share.
F4	Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $191.06 to $192.00 per share.
F5	Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $192.13 to $193.00 per share.
F6	This option was granted pursuant to the 2007 Equity Incentive Plan, as amended, and is exercisable in 25% cumulative annual increments beginning March 10, 2017.