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

Dec 29, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AMERICAN TOWER CORP /MA/ (AMT)
CIK: 0001053507
Period of Report: 2011-12-29

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-12-29	Class A Common Stock	M	21875	$37.70	Acquired	49340	Direct
2011-12-29	Class A Common Stock	S	21875	$60.52	Disposed	27465	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-12-29	Option to Purchase Class A Common Stock	$37.70	M	21875	Disposed	2018-03-17	Class A Common Stock (21875)	Direct

Footnotes

F1: Includes 45 shares acquired under the Company's employee stock purchase plan in November 2011.

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 $60.27 to $60.69 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.