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

Jan 4, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2010-12-30

Reporting Person: DiSanto Edmund (EVP, Chief Admin Officer & GC)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-12-30	Class A Common Stock	M	43750	$37.70	Acquired	58438	Direct
2010-12-30	Class A Common Stock	M	25544	$28.39	Acquired	83982	Direct
2010-12-30	Class A Common Stock	S	69294	$51.30	Disposed	14688	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-12-30	Option to Purchase Class A Common Stock	$37.70	M	43750	Disposed	2018-03-17	Class A Common Stock (43750)	Direct
2010-12-30	Option to Purchase Class A Common Stock	$28.39	M	25544	Disposed	2019-03-10	Class A Common Stock (25544)	Direct

Footnotes

F1: Includes 135 shares and 59 shares acquired under the Company's employee stock purchase plan in May 2010 and November 2010, respectively.

F2: The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan.

F3: Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $51.05 to $51.53 per share.

F4: This option was granted pursuant to the 2007 Equity Incentive Plan and is exercisable in 25% cumulative annual increments beginning March 17, 2009.

F5: This option was granted pursuant to the 2007 Equity Incentive Plan and is exercisable in 25% cumulative annual increments beginning March 10, 2010.