Iron Mountain Incorporated
US ˙ NYSE ˙ US46284V1017

SecurityIRM / Iron Mountain Incorporated
InstitutionSei Investments Co
Latest Disclosed Ownership1,024,664 shares
Latest Disclosed Value $ 84,995,814
Sei Investments Co reports 17.39% increase in ownership of IRM / Iron Mountain Incorporated

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 1,024,664 shares of Iron Mountain Incorporated (US:IRM) valued at $84,995,879 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 872,870 shares of Iron Mountain Incorporated. This represents a change in shares of 17.39% during the quarter. The current value of the position is $131,105,759 USD.

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.

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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)
2026-02-13 2025-12-31 13F IRON MTN INC DEL COM 46284V101 1,024,664 151,794 17.39 84,996 -4.48 0.0839
2025-11-13 2025-09-30 13F IRON MTN INC DEL COM 46284V101 872,870 -12,210 -1.38 88,980 -1.98 0.0957
2025-08-14 2025-06-30 13F IRON MTN INC DEL COM 46284V101 885,080 55,245 6.66 90,783 27.15 0.1052
2025-05-14 2025-03-31 13F/A-1 IRON MTN INC DEL COM 46284V101 829,835 -18,532 -2.18 71,399 -19.93 0.0919
2025-05-13 2025-03-31 13F IRON MTN INC DEL COM 46284V101 849,779 1,412 89,060 0.0969
2025-02-11 2024-12-31 13F IRON MTN INC DEL COM 46284V101 848,367 -68,256 -7.45 89,172 -18.13 0.1145
2024-11-12 2024-09-30 13F IRON MTN INC DEL COM 46284V101 916,623 -208,868 -18.56 108,922 7.99 0.1414
2024-08-13 2024-06-30 13F IRON MTN INC DEL COM 46284V101 1,125,491 181,763 19.26 100,867 33.25 0.1429
2024-05-07 2024-03-31 13F IRON MTN INC DEL COM 46284V101 943,728 68,636 7.84 75,696 23.61 0.1109
2024-02-14 2023-12-31 13F IRON MTN INC DEL COM 46284V101 875,092 643,760 278.28 61,239 345.31 0.0983
2023-11-14 2023-09-30 13F IRON MTN INC DEL COM 46284V101 231,332 -76,050 -24.74 13,753 -21.26 0.0247
2023-08-11 2023-06-30 13F IRON MTN INC DEL COM 46284V101 307,382 119,166 63.31 17,466 75.39 0.0305
2023-05-12 2023-03-31 13F IRON MTN INC DEL COM 46284V101 188,216 70,553 59.96 9,959 69.73 0.0185
2023-02-10 2022-12-31 13F IRON MTN INC DEL COM 46284V101 117,663 -12,947 -9.91 5,867 2.16 0.0130
2022-11-14 2022-09-30 13F IRON MTN INC DEL COM 46284V101 130,610 29,251 28.86 5,743 16.16 0.0128
2022-08-15 2022-06-30 13F IRON MTN INC COM 46284V101 101,359 -53,444 -34.52 4,944 -42.98 0.0107
2022-05-13 2022-03-31 13F IRON MTN INC COM 46284V101 154,803 -18,484 -10.67 8,670 -4.97 0.0174
2022-02-14 2021-12-31 13F IRON MTN INC COM 46284V101 173,287 -15,772 -8.34 9,123 10.73 0.0171
2021-11-12 2021-09-30 13F IRON MTN INC COM 46284V101 189,059 99,516 111.14 8,239 117.04 0.0173
2021-08-06 2021-06-30 13F IRON MTN INC COM 46284V101 89,543 -3,139 -3.39 3,796 10.67 0.0084
2021-05-12 2021-03-31 13F IRON MTN INC COM 46284V101 92,682 34,113 58.24 3,430 98.61 0.0086
2021-02-08 2020-12-31 13F IRON MTN INC COM 46284V101 58,569 -3,120 -5.06 1,727 1.41 0.0045
2020-12-04 2020-09-30 13F/A-1 IRON MTN INC COM 46284V101 61,689 -53,861 -46.61 1,703 -44.29 0.0049
2020-11-06 2020-09-30 13F IRON MTN INC COM 46284V101 73,053 -42,497 2,007 4,832.4098
2020-08-17 2020-06-30 13F/A-1 IRON MTN INC COM 46284V101 115,550 48,112 71.34 3,057 92.02 0.0095
2020-08-11 2020-06-30 13F IRON MTN INC COM 46284V101 63,269 -4,169 1,951 5,292.1914
2020-05-14 2020-03-31 13F IRON MTN INC COM 46284V101 67,438 20,505 43.69 1,592 5.71 0.0058
2020-02-06 2019-12-31 13F IRON MTN INC COM 46284V101 46,933 -45,377 -49.16 1,506 -49.78 0.0045
2019-11-12 2019-09-30 13F IRON MTN INC COM 46284V101 92,310 -21,168 -18.65 2,999 -15.73 0.0077
2019-08-14 2019-06-30 13F IRON MTN INC COM 46284V101 113,478 -2,611 -2.25 3,559 -13.53 0.0116
2019-05-15 2019-03-31 13F IRON MTN INC COM 46284V101 116,089 -52,369 -31.09 4,116 -28.78 0.0138
2019-02-13 2018-12-31 13F IRON MTN INC COM 46284V101 168,458 17,770 11.79 5,779 11.16 0.0206
2018-11-08 2018-09-30 13F IRON MTN INC COM 46284V101 150,688 -9,771 -6.09 5,199 -7.46 0.0188
2018-08-03 2018-06-30 13F IRON MTN INC COM 46284V101 160,459 126,452 371.84 5,618 402.50 0.0191
2018-05-11 2018-03-31 13F IRON MTN INC COM 46284V101 34,007 -13,282 -28.09 1,118 -37.37 0.0043
2018-02-08 2017-12-31 13F IRON MTN INC COM 46284V101 47,289 21,397 82.64 1,785 77.26 0.0062
2017-11-06 2017-09-30 13F IRON MTN INC COM 46284V101 25,892 -1,520 -5.55 1,007 7.01 0.0036
2017-07-31 2017-06-30 13F IRON MTN INC COM 46284V101 27,412 -34,714 -55.88 941 -57.54 0.0038
2017-05-05 2017-03-31 13F IRON MTN INC COM 46284V101 62,126 -63,608 -50.59 2,216 -45.74 0.0097
2017-02-02 2016-12-31 13F IRON MTN INC COM 46284V101 125,734 23,924 23.50 4,084 6.91 0.0198
2016-11-04 2016-09-30 13F IRON MTN INC COM 46284V101 101,810 48,792 92.03 3,820 80.96 0.0194
2016-08-11 2016-06-30 13F IRON MTN INC COM 46284V101 53,018 15,674 41.97 2,111 66.75 0.0127
2016-05-10 2016-03-31 13F/A-1 IRON MTN INC COM 46284V101 37,344 9,845 35.80 1,266 70.39 0.0079
2016-02-03 2015-12-31 13F IRON MTN INC COM 46284V101 27,499 -16,286 -37.20 743 -45.29 0.0045
2015-11-02 2015-09-30 13F/A-1 IRON MTN COM 46284V101 43,785 -35,739 -44.94 1,358 -44.91 0.0125
2015-10-30 2015-09-30 13F DIREXION SHS ETF TR COM 46284V101 43,785 1,360
2015-08-07 2015-06-30 13F/A-1 IRON MTN INC COM 46284V101 79,524 -30,128 -27.48 2,465 -38.37 0.0223
2015-08-04 2015-06-30 13F IRON MTN INC COM 46284V101 79,524 -30,128 2,465 0.0223
2015-05-14 2015-03-31 13F/A-1 IRON MTN INC COM 46284V101 109,652 80,878 281.08 4,000 260.04 0.0347
2015-05-01 2015-03-31 13F IRON MTN INC COM 46284V101 109,652 4,000
2015-02-10 2014-12-31 13F IRON MTN COM 462846106 28,774 28,774 1,111 0.0098
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.