AMERICAN TOWER CORP /MA/ — Director's Dealing 2011

Sep 20, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2011-09-16

Reporting Person: HESS WILLIAM H (EVP, Int'l. Operations)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-09-16	Class A Common Stock	M	4533	$37.52	Acquired	19791	Direct
2011-09-16	Class A Common Stock	M	10937	$37.70	Acquired	30728	Direct
2011-09-16	Class A Common Stock	S	15470	$55.00	Disposed	15258	Direct
2011-09-19	Class A Common Stock	M	81634	$37.52	Acquired	96892	Direct
2011-09-19	Class A Common Stock	M	21875	$37.70	Acquired	118767	Direct
2011-09-19	Class A Common Stock	S	103509	$55.00	Disposed	15258	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-09-16	Option to Purchase Class A Common Stock	$37.52	M	4533	Disposed	2017-03-15	Class A Common Stock (4533)	Direct
2011-09-16	Option to Purchase Class A Common Stock	$37.70	M	10937	Disposed	2018-03-17	Class A Common Stock (10937)	Direct
2011-09-19	Option to Purchase Class A Common Stock	$37.52	M	81634	Disposed	2017-03-15	Class A Common Stock (81634)	Direct
2011-09-19	Option to Purchase Class A Common Stock	$37.70	M	21875	Disposed	2018-03-17	Class A Common Stock (21875)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Class A Common Stock	3662	Indirect

Footnotes

F1: The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan.

F2: This option was granted pursuant to the 2007 Equity Incentive Plan, and is exercisable in 25% cumulative annual increments beginning March 15, 2008.

F3: This option was granted pursuant to the 2007 Equity Incentive Plan, and is exercisable in 25% cumulative annual increments beginning March 17, 2009.