Iron Mountain Incorporated
DE ˙ DB ˙ US46284V1017
109,55 € ↓ -0,60 (-0,54%)
2026-06-04
DEL PRIS
SecurityDE:I5M / Iron Mountain Incorporated
InstitutionCohen & Steers, Inc.
Latest Disclosed Ownership19,106,540 shares
Ownership 6.46%
Cohen & Steers, Inc. ownership in I5M / Iron Mountain Incorporated

2026-02-13 - Cohen & Steers, Inc. has filed an SCHEDULE 13G/A form with the Securities and Exchange Commission (SEC) disclosing ownership of 19,106,540 shares of Iron Mountain Incorporated (DE:I5M). This represents 6.46 percent ownership of the company. In their previous filing dated 2025-11-14 , Cohen & Steers, Inc. had reported owning 16,029,962 shares, indicating an increase of 19.19 percent.

Institutional Ownership: 13D/G Filings

This table shows a history of the 13D/G filings made by the investor and/or investor group. Note that the share values in this table are not directly comparable to any numbers shown in the 13F table (if any).

File
Date		Effective
Date		Form Prev
Shares		 Latest
Shares		 ΔShares
(Percent)		 Ownership
(Percent)		 ΔOwnership
(Percent)
2026-02-13 2026-02-13 13G/A 16,029,962 19,106,540 19.19 6.46 18.97
2025-11-14 2025-11-14 13G 12,788,773 16,029,962 25.34 5.43 24.83
2025-03-07 2025-03-07 13G/A 18,046,503 12,788,773 -29.13 4.35 -29.27
2024-11-14 2024-11-14 13G/A 22,909,485 18,046,503 -21.23 6.15 -21.66
2024-02-14 2024-02-14 13G 22,909,485 7.85

Important Note: One of the primary uses of the 13D/G filings is to evaluate the ability of a firm to control a company (ie, the "beneficial ownership"). To that end, firms are required to report not just direct holdings in companies, but indirect holdings that they control. For investment firms, these indirect holdings can include shares in funds they manage, advisory accounts, and in the case of activist campaigns, pledged votes. Therefore, share counts listed in 13D/G filings can differ significantly than share counts listed in 13F filings.

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)
2026-05-15 2026-03-31 13F Iron Mountain COM 46284V101 16,169,341 -2,734,375 -14.46 1,652 5.29 2.8686
2026-02-13 2025-12-31 13F Iron Mountain COM 46284V101 18,903,716 3,155,034 20.03 1,568 -2.31 2.8349
2025-11-14 2025-09-30 13F Iron Mountain COM 46284V101 15,748,682 1,980,051 14.38 1,605 13.67 2.8957
2025-08-14 2025-06-30 13F Iron Mountain COM 46284V101 13,768,631 286,729 2.13 1,412 21.83 2.5895
2025-05-15 2025-03-31 13F Iron Mountain COM 46284V101 13,481,902 -1,425,944 -9.57 1,160 -25.99 2.1439
2025-02-13 2024-12-31 13F Iron Mountain COM 46284V101 14,907,846 -2,818,166 -15.90 1,567 -25.64 2.9674
2024-11-14 2024-09-30 13F Iron Mountain COM 46284V101 17,726,012 -5,325,004 -23.10 2,106 1.99 3.7474
2024-08-13 2024-06-30 13F Iron Mountain COM 46284V101 23,051,016 -604,022 -2.55 2,066 8.86 4.3305
2024-05-15 2024-03-31 13F Iron Mountain COM 46284V101 23,655,038 1,179,424 5.25 1,897 20.67 3.9709
2024-02-14 2023-12-31 13F Iron Mountain COM 46284V101 22,475,614 15,035,937 202.10 1,573 255.66 3.1825
2023-11-14 2023-09-30 13F Iron Mountain COM 46284V101 7,439,677 -286,090 -3.70 442 0.91 1.0169
2023-08-14 2023-06-30 13F Iron Mountain COM 46284V101 7,725,767 4,798,010 163.88 439 184.42 0.9247
2023-05-15 2023-03-31 13F Iron Mountain COM 46284V101 2,927,757 2,927,651 2,761,934.91 155 2,980.00 0.3346
2023-02-14 2022-12-31 13F Iron Mountain COM 46284V101 106 -693,554 -99.98 5 -99.98 0.0000
2022-11-14 2022-09-30 13F Iron Mountain COM 46284V101 693,660 693,499 430,744.72 30,500 381,150.00 0.0682
2022-08-15 2022-06-30 13F Iron Mountain COM 46284V101 161 -4,586 -96.61 8 -96.96 0.0000
2022-05-16 2022-03-31 13F Iron Mountain COM 46284V101 4,747 -1,597 -25.17 263 -20.78 0.0004
2022-02-14 2021-12-31 13F Iron Mountain COM 46284V101 6,344 6,344 332 0.0005
2021-11-15 2021-09-30 13F Iron Mountain COM 46284V101 0 -14,348 -100.00 0 -100.00
2021-08-16 2021-06-30 13F Iron Mountain COM 46284V101 14,348 490 3.54 607 18.32 0.0012
2021-05-17 2021-03-31 13F Iron Mountain COM 46284V101 13,858 -566,223 -97.61 513 -97.00 0.0011
2021-02-16 2020-12-31 13F Iron Mountain COM 46284V101 580,081 43,661 8.14 17,101 19.00 0.0411
2020-11-16 2020-09-30 13F Iron Mountain COM 46284V101 536,420 -2,769,845 -83.78 14,371 -83.35 0.0383
2020-08-14 2020-06-30 13F Iron Mountain COM 46284V101 3,306,265 3,306,265 86,294 0.2408
2019-11-14 2019-09-30 13F Iron Mountain COM 46284V101 0 -6,518,367 -100.00 0 -100.00
2019-08-14 2019-06-30 13F Iron Mountain COM 46284V101 6,518,367 -2,352,730 -26.52 204,025 -35.14 0.5658
2019-05-15 2019-03-31 13F Iron Mountain COM 46284V101 8,871,097 -2,099,676 -19.14 314,569 -11.53 0.8727
2019-02-14 2018-12-31 13F Iron Mountain COM 46284V101 10,970,773 4,456,942 68.42 355,563 58.13 1.1311
2018-11-16 2018-09-30 13F/A-1 Iron Mountain COM 46284V101 6,513,831 775,629 13.52 224,857 11.93 0.6537
2018-11-14 2018-09-30 13F Iron Mountain COM 46284V101 6,513,831 775,629 224,857
2018-08-14 2018-06-30 13F Iron Mountain COM 46284V101 5,738,202 3,773,693 192.09 200,894 211.20 0.5753
2018-05-14 2018-03-31 13F Iron Mountain COM 46284V101 1,964,509 1,964,509 64,554 0.1975
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.