AMERICAN TOWER CORP /MA/ — Director's Dealing 2012

Mar 13, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2012-03-10

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-03-10	Common Stock	M	7864	—	Acquired	19497	Direct
2012-03-10	Common Stock	F	2617	$62.22	Disposed	16880	Direct
2012-03-10	Common Stock	M	5219	—	Acquired	22099	Direct
2012-03-10	Common Stock	F	2179	$62.22	Disposed	19920	Direct
2012-03-10	Common Stock	M	5170	—	Acquired	25090	Direct
2012-03-10	Common Stock	F	2159	$62.22	Disposed	22931	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-03-10	Restricted Stock Units	$	M	7864	Disposed		Common Stock (7864)	Direct
2012-03-10	Restricted Stock Units	$	M	5219	Disposed		Common Stock (5219)	Direct
2012-03-10	Restricted Stock Units	$	M	5170	Disposed		Common Stock (5170)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	5095	Indirect

Footnotes

F1: Each Restricted Stock Unit (RSU) respresents a contingent right to receive one share of Common Stock.

F2: This RSU was granted on March 10, 2009 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2010. This Form 4 reflects the vesting of this RSU on March 10, 2012 as to 75% of the original grant amount.

F3: This RSU was granted on March 10, 2010 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2011. This Form 4 reflects the vesting of this RSU on March 10, 2012 as to 50% of the original grant amount.

F4: This RSU was granted on March 10, 2011 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2012. This Form 4 reflects the vesting of this RSU on March 10, 2012 as to 25% of the original grant amount.