AMERICAN TOWER CORP /MA/ — Director's Dealing 2017

May 2, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2017-04-28

Reporting Person: Meyer Robert Joseph JR (SVP, Finance & Corp Controller)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-04-28	Common Stock	M	10000	$43.11	Acquired	36060	Direct
2017-04-28	Common Stock	M	11690	$50.78	Acquired	47750	Direct
2017-04-28	Common Stock	S	21690	$125.78	Disposed	26060	Direct
2017-05-01	Common Stock	M	15796	$62.00	Acquired	41856	Direct
2017-05-01	Common Stock	S	18963	$126.59	Disposed	22893	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-04-28	Option to Purchase Common Stock	$43.11	M	10000	Disposed	2020-03-10	Common Stock (10000)	Direct
2017-04-28	Option to Purchase Common Stock	$50.78	M	11690	Disposed	2021-03-10	Common Stock (11690)	Direct
2017-05-01	Option to Purchase Common Stock	$62.00	M	15796	Disposed	2022-03-12	Common Stock (15796)	Direct

Footnotes

F1: Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $125.50 to $126.03 per share.

F2: Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $126.50 to $126.65 per share.

F3: This option was granted pursuant to the 2007 Equity Incentive Plan, as amended (the "2007 Plan"), and is exercisable in 25% cumulative annual increments beginning March 10, 2011.

F4: This option was granted pursuant to the 2007 Plan and is exercisable in 25% cumulative annual increments beginning March 10, 2012.

F5: This option was granted pursuant to the 2007 Plan and is exercisable in 25% cumulative annual increments beginning March 12, 2013.