(AMT)

Role: EVP, CFO & Treasurer
Signature: /s/ Marina A. Breed, as attorney-in-fact
Stock symbol: AMT
Transactions as of: Mar 6, 2024
Transactions value $: -$1,433,385
Form type: 4
Date filed: 3/8/2024, 05:07 PM
Previous filing: Mar 5, 2024
Next filing: Mar 12, 2024

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	AMT	Common Stock	Options Exercise	$934K	+11.5K	+18.28%	$81.18	74.5K	Mar 6, 2024	Direct
transaction	AMT	Common Stock	Sale	-$1.95M	-9.5K	-12.75%	$205.56	65K	Mar 6, 2024	Direct	F1, F2
transaction	AMT	Common Stock	Sale	-$416K	-2.01K	-3.1%	$206.44	63K	Mar 6, 2024	Direct	F1, F3

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	-11.5K	-100%	$0.00^*	0	Mar 6, 2024	Common Stock	11.5K	$81.18	Direct	F4

* 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	The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 9, 2023.
F2	Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $205.14 to $206.12 per share.
F3	Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $206.21 to $206.61 per share.
F4	This option was granted pursuant to the 2007 Equity Incentive Plan, as amended, and is exercisable in 25% cumulative annual increments beginning March 10, 2015.