X0303 4 2010-12-30 0001053507 AMERICAN TOWER CORP /MA/ AMT 0001393458 DiSanto Edmund 116 HUNTINGTON AVENUE BOSTON MA 02116 0 1 0 0 EVP, Chief Admin Officer & GC Class A Common Stock 2010-12-30 4 M 0 43750 37.70 A 58438 D Class A Common Stock 2010-12-30 4 M 0 25544 28.39 A 83982 D Class A Common Stock 2010-12-30 4 S 0 69294 51.30 D 14688 D Option to Purchase Class A Common Stock 37.70 2010-12-30 4 M 0 43750 0 D 2018-03-17 Class A Common Stock 43750 43750 D Option to Purchase Class A Common Stock 28.39 2010-12-30 4 M 0 25544 0 D 2019-03-10 Class A Common Stock 25544 76630 D Includes 135 shares and 59 shares acquired under the Company's employee stock purchase plan in May 2010 and November 2010, respectively. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. Represents the weighted average price of shares sold in multiple same-day transactions at prices ranging from $51.05 to $51.53 per share. This option was granted pursuant to the 2007 Equity Incentive Plan and is exercisable in 25% cumulative annual increments beginning March 17, 2009. This option was granted pursuant to the 2007 Equity Incentive Plan and is exercisable in 25% cumulative annual increments beginning March 10, 2010. /s/ Mneesha O. Nahata, as attorney-in-fact 2011-01-04