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

Dec 5, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2011-12-01

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-11-09	Class A Common Stock	G	8500	—	Disposed	5814	Direct
2011-12-01	Class A Common Stock	M	28723	$37.52	Acquired	34537	Direct
2011-12-01	Class A Common Stock	M	10938	$37.70	Acquired	45475	Direct
2011-12-01	Class A Common Stock	S	39661	$58.75	Disposed	5814	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-12-01	Option to Purchase Class A Common Stock	$37.52	M	28723	Disposed	2017-03-15	Class A Common Stock (28723)	Direct
2011-12-01	Option to Purchase Class A Common Stock	$37.70	M	10938	Disposed	2018-03-17	Class A Common Stock (10938)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Class A Common Stock	5095	Indirect

Footnotes

F1: Gift of Class A Common Stock to various charitable organizations through a donor advised fund.

F2: Includes 489 shares acquired under the Company's employee stock purchase plan in May 2011. 2,678 shares were previously reported as directly owned, but were contributed to a grantor retained annuity trust ("GRAT") on October 29, 2010. 1,245 shares were returned to the reporting person's direct beneficial ownership on November 9, 2011 in the form of a scheduled annuity payment under the terms of the GRAT.

F3: The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan.

F4: Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $58.39 to $59.39 per share.

F5: This option was granted pursuant to the 2007 Equity Incentive Plan, and is exercisable in 25% cumulative annual increments beginning March 15, 2008.

F6: This option was granted pursuant to the 2007 Equity Incentive Plan, and is exercisable in 25% cumulative annual increments beginning March 17, 2009.