X0306 4 2018-06-14 0 0001020569 IRON MOUNTAIN INC IRM 0001184214 HALVORSEN KRIS 11 MCINNIS PARKWAY SAN RAFAEL CA 94903 1 0 0 0 Phantom Stock 2018-06-14 4 A 0 4413 0.01 A Common Stock 4413 22380.04 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 June 14, 2018, which RSUs vest on the grant date, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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. /s/ Elizabeth Tammaro, under Power of Attorney dated May 26, 2016, from Per-Kristian Halvorsen 2018-06-18