Matlock Robin

SEC source: 0001781215-26-000017 · wk-form4_1788293660.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,037

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Of the shares reported, 1 share is attributable to the Reporting Person's unvested RSUs and remains subject to the same vesting conditions as the underlying RSUs. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001781215-26-000015 · wk-form4_1780430730.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,031

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Of the shares reported, 1 share is attributable to the Reporting Person's unvested RSUs and remains subject to the same vesting conditions as the underlying RSUs. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001781215-26-000013 · wk-form4_1778534305.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,451.189

F1 · shares: Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 7, 2026. The RSUs vest in their entirety on the grant date.

SEC source: 0001781215-26-000011 · wk-form4_1778011542.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,025

F1 · shares: Restricted stock units vesting on May 1, 2027. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001781215-26-000008 · wk-form4_1772571788.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,637

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001781215-26-000006 · wk-form4_1769119506.xml · derivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 10.189 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: Settlement of the Phantom Shares is in Common Stock

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001781215-26-000006 · wk-form4_1769119506.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 28,559.189

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001781215-26-000004 · wk-form4_1767911178.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10.189

Underlying: Common Stock · 10.189 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Common Stock were acquired in multiple transactions at prices ranging from $84.304 to $84.979, inclusive. The Reporting Person undertakes to provide the Company, any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock acquired at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001781215-26-000002 · wk-form4_1767741431.xml · derivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 998 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: Settlement of the Phantom Shares is in Common Stock.

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001781215-26-000002 · wk-form4_1767741431.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 28,549

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001781215-25-000009 · wk-form4_1764709694.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,632

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001781215-25-000007 · wk-form4_1759867755.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 998

Underlying: Common Stock · 7.446 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Common Stock were acquired in multiple transactions at prices ranging from $104.349 to $104.524, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock acquired at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001781215-25-000005 · wk-form4_1756843346.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,628

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-25-000158 · wk-form4_1752008930.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 990.554

Underlying: Common Stock · 7.673 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $100.419 to $100.594, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001408198-25-000162 · wk-form4_1748980806.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,624

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-25-000130 · wk-form4_1748895669.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 27,551

F1 · shares: Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 29, 2025. The RSUs vest in their entirety on the grant date.

SEC source: 0001408198-25-000138 · wk-form4_1746475298.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,620

F1 · shares: Restricted stock units vesting on May 1, 2026. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-25-000082 · wk-form4_1744063656.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 982.881

Underlying: Common Stock · 9.552 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Common Stock were acquired in multiple transactions at prices ranging from $79.524 to $80.259, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote.

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001408198-25-000079 · wk-form4_1741122109.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,235

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-25-000025 · wk-form4_1736544699.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 973.329

Underlying: Common Stock · 13.253 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $103.329 to $103.734, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001020569-25-000013 · wk-form4_1736202753.xml · derivative · entry 3

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 960.076

Underlying: Common Stock · 960.085 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), phantom stock were settled in cash on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each phantom stock represents a contingent right to receive a cash payment equal to the value on the settlement date of one share of Iron Mountain Incorporated common stock ("Common Stock").

F3 · shares: Settlement of the Phantom Shares is in cash.

F1 · price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), phantom stock were settled in cash on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each phantom stock represents a contingent right to receive a cash payment equal to the value on the settlement date of one share of Iron Mountain Incorporated common stock ("Common Stock").

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), phantom stock were settled in cash on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each phantom stock represents a contingent right to receive a cash payment equal to the value on the settlement date of one share of Iron Mountain Incorporated common stock ("Common Stock").

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), phantom stock were settled in cash on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each phantom stock represents a contingent right to receive a cash payment equal to the value on the settlement date of one share of Iron Mountain Incorporated common stock ("Common Stock").

SEC source: 0001020569-25-000013 · wk-form4_1736202753.xml · nonDerivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 24,342

F2 · shares: Represents Common Stock otherwise issuable to the Reporting Person for which cash was paid, based on the closing price of Common Stock on the New York Stock Exchange on the settlement date.

SEC source: 0001020569-25-000013 · wk-form4_1736202753.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,302.085

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), phantom stock were settled in cash on various dates selected by the Reporting Person or as otherwise provided in the Plan. Each phantom stock represents a contingent right to receive a cash payment equal to the value on the settlement date of one share of Iron Mountain Incorporated common stock ("Common Stock").

SEC source: 0001020569-25-000029 · wk-form4a_1737151055.xml · derivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 973.329

Underlying: Common Stock · 960.085 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), the Phantom Shares will become payable in shares of 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.

F3 · shares: Settlement of the Phantom Shares is in Common Stock.

F2 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), the Phantom Shares will become payable in shares of 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.

F2 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), the Phantom Shares will become payable in shares of 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.

SEC source: 0001020569-25-000029 · wk-form4a_1737151055.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,302

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: On January 6, 2025, the Reporting Person filed a Form 4 which inadvertently included an incorrect distribution type due to an administrative error. This amendment is being filed solely to reflect that the shares of phantom stock (the "Phantom Shares") were distributed in shares of Iron Mountain Incorporated common stock ("Common Stock") instead of in cash. Only whole shares of Common Stock were transferred in-kind; fractional shares were sold and settled in cash.

F2 · price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), the Phantom Shares will become payable in shares of 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.

SEC source: 0001408198-24-000180 · wk-form4_1733259642.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,232

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-24-000239 · wk-form4_1728334199.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,920.161

Underlying: Common Stock · 11.48 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $118.729 to $119.114, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

SEC source: 0001408198-24-000157 · wk-form4_1725480178.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,229

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-24-000186 · wk-form4_1720489841.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,908.681

Underlying: Common Stock · 13.338 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $92.129 to $92.459, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

SEC source: 0001408198-24-000120 · wk-form4_1717532785.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,226

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-24-000149 · wk-form4_1717449156.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 24,342

F1 · shares: Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 30, 2024. The RSUs vest on the grant date.

SEC source: 0001408198-24-000108 · wk-form4_1714766609.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,223

F1 · shares: Restricted stock units vesting on May 1, 2025. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-24-000093 · wk-form4_1712349873.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,895.343

Underlying: Common Stock · 15.26 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $79.989 to $80.149, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

SEC source: 0001408198-24-000040 · wk-form4_1709586359.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 773

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-24-000014 · wk-form4_1704754396.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,880.083

Underlying: Common Stock · 26.972 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated common stock ("Common Stock") were sold in multiple transactions at prices ranging from $67.269 to $67.379, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("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.

SEC source: 0001020569-24-000002 · wk-form4_1704406623.xml · derivative · entry 3

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,853.111

Underlying: Common Stock · 940.666 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F3 · shares: Settlement of the Phantom Shares is in cash.

F4 · derivative.exercise_date: Settlement of the Phantom Shares is made in accordance with distribution election made by the Reporting Person or as otherwise provided in the Plan.

F4 · derivative.expiration_date: Settlement of the Phantom Shares is made in accordance with distribution election made by the Reporting Person or as otherwise provided in the Plan.

SEC source: 0001020569-24-000002 · wk-form4_1704406623.xml · nonDerivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 21,957

F2 · shares: Represents Common Stock otherwise issuable to the Reporting Person for which cash was paid.

SEC source: 0001020569-24-000002 · wk-form4_1704406623.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,897.666

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001408198-23-000072 · wk-form4_1701723715.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 771

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-23-000200 · wk-form4_1696972085.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,793.777

Underlying: Common Stock · 31.079 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated Common Stock were purchased in multiple transactions at prices ranging from $57.639 to $57.869, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock purchased at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001020569-23-000147 · wf-form4_168902842637956.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,762.698

Underlying: Common Stock · 29.367 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated Common Stock were purchased in multiple transactions at prices ranging from $57.50 to $57.60, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock purchased at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001209191-23-033677 · doc4.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 769

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-23-000114 · wf-form4_168376706584262.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 21,957

F1 · shares: Consists of shares issuable upon the settlement of restricted stock units ("RSUs") granted on May 9, 2023. The RSUs vest on the grant date.

SEC source: 0001209191-23-026916 · doc4.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 767

F1 · shares: Restricted stock units vesting on May 1, 2024. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-23-000095 · wf-form4_168089998179420.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,733.331

Underlying: Common Stock · 31.764 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F3 · price: The price reported in Column 8 is a weighted average price. These shares of Iron Mountain Incorporated Common Stock were sold in multiple transactions at prices ranging from $52.52 to $52.71, inclusive. The Reporting Person undertakes to provide Iron Mountain Incorporated (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock sold at each separate price within the ranges set forth in this footnote (3).

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001209191-23-014574 · doc4.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 384

F1 · shares: Shares acquired by the Reporting Person in connection with MSCI Inc.'s payment of a dividend. Pursuant to the MSCI Inc. Non-Employee Directors Deferral Plan, the Reporting Person has elected to defer receipt of the shares until the earlier of June 1, 2033 and the 60th day after such Reporting Person's "separation from service" as a director.

SEC source: 0001020569-23-000013 · wf-form4_167330008256439.xml · derivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,701.567

Underlying: Common Stock · 44.19 shares

Expires not disclosed

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F2 · shares: These shares give effect to dividends paid on Common Stock as if reinvested in Phantom Shares.

F1 · derivative.exercise_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F1 · derivative.expiration_date: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

SEC source: 0001020569-23-000004 · wf-form4_167296565995753.xml · derivative · entry 3

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,657.377

Underlying: Common Stock · 885.392 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.

F3 · shares: Settlement of the Phantom Shares is in cash.

F4 · derivative.exercise_date: Settlement of the Phantom Shares is made in accordance with distribution elections made by the Reporting Person or as otherwise provided in the Plan.

F4 · derivative.expiration_date: Settlement of the Phantom Shares is made in accordance with distribution elections made by the Reporting Person or as otherwise provided in the Plan.

SEC source: 0001020569-23-000004 · wf-form4_167296565995753.xml · nonDerivative · entry 2

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,910

F2 · shares: Represents Common Stock otherwise issuable to the Reporting Person for which cash was paid, based on the closing price of Common Stock on the New York Stock Exchange on the transaction date.

SEC source: 0001020569-23-000004 · wf-form4_167296565995753.xml · nonDerivative · entry 1

Matlock Robin · CIK 0001781215 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 19,795.392

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan (the "Plan"), 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.