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

Mar 21, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2011-03-17

Reporting Person: TAICLET JAMES D JR (Director, Chairman, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-03-17	Class A Common Stock	M	11607	—	Acquired	54031	Direct
2011-03-17	Class A Common Stock	F	4846	$51.04	Disposed	49185	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-03-17	Restricted Stock Units	$	M	11607	Disposed		Class A Common Stock (11607)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Class A Common Stock	1000	Indirect

Footnotes

F1: Mr. Taiclet disclaims beneficial ownership in shares owned by minor children.

F2: Each Restricted Stock Unit (RSU) respresents a contingent right to receive one share of Class A Common Stock.

F3: This RSU was granted on March 17, 2008 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 17, 2009. This Form 4 reflects the vesting of this RSU on March 17, 2011 as to 75% of the original grant amount.