X0306 4 2015-05-28 0 0001020569 IRON MOUNTAIN INC IRM 0001244482 ANTENUCCI TED R C/O IRON MOUNTAIN INCORPORATED ONE FEDERAL STREET BOSTON MA 02110 1 0 0 0 Phantom Stock 2015-05-28 4 A 0 3673 0.01 A Common Stock 3673 18475.5355 D Phantom Stock 2015-05-28 4 A 0 103.5 36.81 A Common Stock 103.5 18579.0355 D Phantom Stock 2015-05-28 4 A 0 225 36.8172 A Common Stock 225 18804.0355 D Phantom Stock 2015-05-28 4 A 0 0.25 36.7391 A Common Stock 0.25 18804.2855 D Phantom Stock 2015-05-28 4 A 0 0.1298 36.8149 A Common Stock 0.1298 18804.4153 D Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan") with respect to certain restricted stock units ("RSUs") received on May 28, 2015, which RSUs vest on the grant date, the shares of phantom stock (the "Phantom Shares") will become payable in Iron Mountain Incorporated common stock following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of common stock. Pursuant to the Reporting Person's election to participate in the Plan, the Phantom Shares will become payable in shares of Iron Mountain Incorporated common stock on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each Phantom Share is the economic equivalent of one share of common stock. These shares give effect to dividends paid on previously reported RSUs as if reinvested in Phantom Shares. /s/ Sarah Cammarata, under Power of Attorney dated June 21, 2011, from Ted Antenucci 2015-06-01