Iron Mountain Incorporated
MX ˙ BMV ˙ US46284V1017
SecurityMX:IRM1 / Iron Mountain Incorporated
InstitutionRockefeller Capital Management L.P.
Latest Disclosed Ownership389,140 shares
Latest Disclosed Value $ 39,746,929
Rockefeller Capital Management L.P. reports 3.68% decrease in ownership of IRM1 / Iron Mountain Incorporated

On May 14, 2026 - Rockefeller Capital Management L.P. filed a 13F-HR form disclosing ownership of 389,140 shares of Iron Mountain Incorporated (MX:IRM1) valued at $39,746,929 USD as of March 31, 2026. The entity filed a previous 13F-HR/A on March 16, 2026 disclosing 403,992 shares of Iron Mountain Incorporated. This represents a change in shares of -3.68% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel .

Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-14 2026-03-31 13F IRON MTN INC DEL COM 46284V101 389,140 -14,852 -3.68 39,747 18.27 0.0705
2026-03-16 2025-12-31 13F/A-1 IRON MTN INC DEL COM 46284V101 403,992 -3,463 -0.85 33,607 -19.26 0.0605
2026-02-14 2025-12-31 13F IRON MTN INC DEL COM 46284V101 403,993 -3,462 33,607 0.0307
2025-11-14 2025-09-30 13F IRON MTN INC DEL COM 46284V101 407,455 28,566 7.54 41,623 -5.26 0.0814
2025-08-14 2025-06-30 13F/A-1 IRON MTN INC DEL COM 46284V101 378,889 -48,676 -11.38 43,935 19.11 0.0963
2025-08-08 2025-06-30 13F IRON MTN INC DEL COM 46284V101 378,831 -48,734 43,929 0.0554
2025-05-14 2025-03-31 13F IRON MTN INC DEL COM 46284V101 427,565 114,692 36.66 36,886 12.23 0.0910
2025-02-13 2024-12-31 13F IRON MTN INC DEL COM 46284V101 312,873 -267,946 -46.13 32,868 -52.36 0.0851
2024-11-14 2024-09-30 13F IRON MTN INC DEL COM 46284V101 580,819 -182,825 -23.94 68,990 0.82 0.1857
2024-08-12 2024-06-30 13F IRON MTN INC DEL COM 46284V101 763,644 101,427 15.32 68,431 28.83 0.1945
2024-05-14 2024-03-31 13F IRON MTN INC DEL COM 46284V101 662,217 -119,634 -15.30 53,117 -2.92 0.1550
2024-02-14 2023-12-31 13F IRON MTN INC DEL COM 46284V101 781,851 -53,706 -6.43 54,714 10.15 0.1828
2023-11-14 2023-09-30 13F IRON MTN INC DEL COM 46284V101 835,557 -61,378 -6.84 49,674 -2.53 0.1916
2023-08-14 2023-06-30 13F IRON MTN INC DEL COM 46284V101 896,935 -96,131 -9.68 50,964 97,905.77 0.1974
2023-05-16 2023-03-31 13F IRON MTN INC DEL COM 46284V101 993,066 410,773 70.54 53 -99.82 0.2260
2023-03-06 2022-12-31 13F IRON MTN INC DEL COM 46284V101 582,293 -499,298 -46.16 29,026 -38.97 0.1459
2022-11-02 2022-09-30 13F IRON MTN INC DEL COM 46284V101 1,081,591 -2,683 -0.25 47,557 -9.91 0.2458
2022-08-12 2022-06-30 13F IRON MTN INC COM 46284V101 1,084,274 -28,819 -2.59 52,791 -14.40 0.2805
2022-05-13 2022-03-31 13F IRON MTN INC COM 46284V101 1,113,093 -40,779 -3.53 61,674 2.14 0.2974
2022-02-14 2021-12-31 13F IRON MTN INC COM 46284V101 1,153,872 409,697 55.05 60,381 86.75 0.2818
2021-11-12 2021-09-30 13F IRON MTN INC COM 46284V101 744,175 21,724 3.01 32,333 5.76 0.1699
2021-08-10 2021-06-30 13F IRON MTN INC COM 46284V101 722,451 -20,242 -2.73 30,573 11.23 0.1722
2021-05-11 2021-03-31 13F IRON MTN INC COM 46284V101 742,693 31,013 4.36 27,486 31.02 0.1860
2021-02-12 2020-12-31 13F IRON MTN INC COM 46284V101 711,680 103,642 17.05 20,979 28.80 0.1589
2020-11-13 2020-09-30 13F IRON MTN INC COM 46284V101 608,038 -17,176 -2.75 16,288 -0.19 0.1526
2020-08-12 2020-06-30 13F IRON MTN INC COM 46284V101 625,214 15,520 2.55 16,319 12.46 0.1708
2020-05-12 2020-03-31 13F IRON MTN INC COM 46284V101 609,694 37,582 6.57 14,511 -20.41 0.1904
2020-02-07 2019-12-31 13F IRON MTN INC COM 46284V101 572,112 20,964 3.80 18,233 2.13 0.2273
2019-11-12 2019-09-30 13F IRON MTN INC COM 46284V101 551,148 5,780 1.06 17,852 4.58 0.2422
2019-08-09 2019-06-30 13F IRON MTN INC COM 46284V101 545,368 -10,711 -1.93 17,070 -13.43 0.2380
2019-05-10 2019-03-31 13F IRON MTN INC COM 46284V101 556,079 -1,472 -0.26 19,718 9.12 0.2810
2019-02-12 2018-12-31 13F IRON MTN INC COM 46284V101 557,551 -11,374 -2.00 18,070 -7.99 0.3167
2018-11-02 2018-09-30 13F Iron Mountain Common 46284V101 568,925 -11,020 -1.90 19,639 -3.28 0.2981
2018-07-31 2018-06-30 13F Iron Mountain Common 46284V101 579,945 25,876 4.67 20,304 11.52 0.3306
2018-05-09 2018-03-31 13F Iron Mountain Common 46284V101 554,069 554,069 18,207 0.3009
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.