Iron Mountain Incorporated
MX ˙ BMV ˙ US46284V1017
SecurityMX:IRM1 / Iron Mountain Incorporated
InstitutionNomura Asset Management Co Ltd
Latest Disclosed Ownership563,343 shares
Latest Disclosed Value $ 57,539,854
Nomura Asset Management Co Ltd reports 3.46% increase in ownership of IRM1 / Iron Mountain Incorporated

On May 11, 2026 - Nomura Asset Management Co Ltd filed a 13F-HR form disclosing ownership of 563,343 shares of Iron Mountain Incorporated (MX:IRM1) valued at $57,539,854 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 10, 2026 disclosing 544,483 shares of Iron Mountain Incorporated. This represents a change in shares of 3.46% 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.

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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)
2026-05-11 2026-03-31 13F IRON MTN INC DEL COM 46284V101 563,343 18,860 3.46 57,540 27.40 0.0929
2026-02-10 2025-12-31 13F IRON MTN INC DEL COM 46284V101 544,483 15,435 2.92 45,165 -16.26 0.1143
2025-11-12 2025-09-30 13F IRON MTN INC DEL COM 46284V101 529,048 11,330 2.19 53,931 1.56 0.1408
2025-08-11 2025-06-30 13F IRON MTN INC DEL COM 46284V101 517,718 19,609 3.94 53,102 23.91 0.1456
2025-05-12 2025-03-31 13F IRON MTN INC DEL COM 46284V101 498,109 23,518 4.96 42,857 -14.09 0.1312
2025-02-12 2024-12-31 13F IRON MTN INC DEL COM 46284V101 474,591 18,296 4.01 49,884 -8.00 0.1501
2024-11-15 2024-09-30 13F IRON MTN INC DEL COM 46284V101 456,295 7,023 1.56 54,222 34.67 0.1672
2024-08-14 2024-06-30 13F IRON MTN INC DEL COM 46284V101 449,272 24,490 5.77 40,264 18.17 0.1372
2024-05-13 2024-03-31 13F IRON MTN INC DEL COM 46284V101 424,782 11,911 2.88 34,072 17.93 0.1237
2024-02-09 2023-12-31 13F IRON MTN INC DEL COM 46284V101 412,871 7,210 1.78 28,893 19.80 0.1194
2023-11-03 2023-09-30 13F IRON MTN INC DEL COM 46284V101 405,661 3,657 0.91 24,117 5.58 0.1130
2023-08-14 2023-06-30 13F IRON MTN INC DEL COM 46284V101 402,004 9,200 2.34 22,842 9.90 0.1052
2025-01-10 2023-03-31 13F/A-1 IRON MTN INC DEL COM 46284V101 392,804 4,821 1.24 20,783 7.46 0.1092
2023-05-11 2023-03-31 13F IRON MTN INC DEL COM 46284V101 392,804 4,821 20,783 0.1092
2025-01-10 2022-12-31 13F/A-1 IRON MTN INC DEL COM 46284V101 387,983 25,074 6.91 19,341 21.20 0.1124
2023-02-14 2022-12-31 13F IRON MTN INC DEL COM 46284V101 387,983 25,074 19,341 0.1124
2025-01-10 2022-09-30 13F/A-3 IRON MTN INC DEL COM 46284V101 362,909 18,549 5.39 15,957 -4.83 0.1016
2022-11-14 2022-09-30 13F/A-2 IRON MTN INC DEL COM 46284V101 362,909 18,549 15,957 0.1016
2022-11-10 2022-09-30 13F/A-1 IRON MTN INC DEL COM 46284V101 362,909 18,549 15,957 0.1016
2022-11-10 2022-09-30 13F IRON MTN INC DEL COM 46284V101 362,909 18,549 15,957 0.0642
2025-01-10 2022-06-30 13F/A-1 IRON MTN INC COM 46284V101 344,360 9,536 2.85 16,767 -9.63 0.1047
2022-08-12 2022-06-30 13F IRON MTN INC COM 46284V101 344,360 9,536 16,767 0.1034
2025-01-10 2022-03-31 13F/A-1 IRON MTN INC COM 46284V101 334,824 -10,630 -3.08 18,553 2.63 0.1009
2022-05-13 2022-03-31 13F IRON MTN INC COM 46284V101 334,824 -10,630 18,553 0.1009
2025-01-10 2021-12-31 13F/A-2 IRON MTN INC COM 46284V101 345,454 21,438 6.62 18,078 28.41 0.0913
2022-02-01 2021-12-31 13F IRON MTN INC COM 46284V101 345,454 21,438 18,078 0.0913
2025-01-10 2021-09-30 13F/A-2 IRON MTN INC COM 46284V101 324,016 -28,761 -8.15 14,078 -5.70 0.0794
2021-11-12 2021-09-30 13F IRON MTN INC COM 46284V101 324,016 -28,761 14,078 0.0795
2025-01-10 2021-06-30 13F/A-2 IRON MTN INC COM 46284V101 352,777 -3,094 -0.87 14,930 13.36 0.0864
2021-08-06 2021-06-30 13F IRON MTN INC COM 46284V101 352,777 -3,094 14,930 0.0865
2025-01-10 2021-03-31 13F/A-2 IRON MTN INC COM 46284V101 355,871 57,206 19.15 13,171 49.59 0.0839
2021-05-14 2021-03-31 13F IRON MTN INC COM 46284V101 355,871 57,206 13,171 0.0839
2025-01-10 2020-12-31 13F/A-2 IRON MTN INC COM 46284V101 298,665 9,547 3.30 8,805 13.67 0.0592
2021-02-12 2020-12-31 13F IRON MTN INC COM 46284V101 298,665 9,547 8,804 0.0592
2020-11-12 2020-09-30 13F IRON MTN INC COM 46284V101 289,118 22,325 8.37 7,745 11.21 0.0595
2020-08-13 2020-06-30 13F IRON MTN INC COM 46284V101 266,793 6,260 2.40 6,964 12.32 0.0589
2020-05-14 2020-03-31 13F IRON MTN INC COM 46284V101 260,533 5,356 2.10 6,200 -23.76 0.0641
2020-02-13 2019-12-31 13F IRON MTN INC COM 46284V101 255,177 16,280 6.81 8,132 5.08 0.0729
2019-11-13 2019-09-30 13F IRON MTN INC COM 46284V101 238,897 4,243 1.81 7,739 5.38 0.0739
2019-08-13 2019-06-30 13F IRON MTN INC COM 46284V101 234,654 -2,264 -0.96 7,344 -12.58 0.0726
2019-05-10 2019-03-31 13F/A-1 IRON MTN INC COM 46284V101 236,918 -1,731 -0.73 8,401 8.61 0.0826
2019-05-10 2019-03-31 13F IRON MTN INC COM 46284V101 236,918 -1,731 8,401
2019-02-12 2018-12-31 13F IRON MTN INC COM 46284V101 238,649 4,960 2.12 7,735 -4.12 0.0864
2018-11-07 2018-09-30 13F IRON MTN INC COM 46284V101 233,689 11,540 5.19 8,067 3.73 0.0783
2018-08-03 2018-06-30 13F IRON MTN INC COM 46284V101 222,149 -2,304 -1.03 7,777 5.44 0.0807
2018-05-14 2018-03-31 13F IRON MTN INC COM 46284V101 224,453 14,091 6.70 7,376 -7.07 0.0805
2018-02-14 2017-12-31 13F IRON MTN INC COM 46284V101 210,362 9,371 4.66 7,937 1.52 0.0919
2017-11-13 2017-09-30 13F IRON MTN INC COM 46284V101 200,991 8,091 4.19 7,818 17.95 0.1010
2017-08-14 2017-06-30 13F IRON MTN INC COM 46284V101 192,900 1,019 0.53 6,628 -3.17 0.0892
2017-06-28 2017-03-31 13F/A-1 IRON MTN INC COM 46284V101 191,881 1,101 0.58 6,845 10.44 0.0964
2017-05-12 2017-03-31 13F IRON MTN INC COM 46284V101 191,881 6,845
2017-02-14 2016-12-31 13F IRON MTN INC COM 46284V101 190,780 10,540 5.85 6,198 -8.37 0.1117
2016-11-10 2016-09-30 13F IRON MTN INC COM 46284V101 180,240 1,650 0.92 6,764 -4.91 0.1213
2016-08-12 2016-06-30 13F IRON MTN INC COM 46284V101 178,590 36,400 25.60 7,113 47.51 0.1331
2016-05-13 2016-03-31 13F IRON MTN INC COM 46284V101 142,190 9,143 6.87 4,822 34.17 0.0919
2016-02-12 2015-12-31 13F IRON MTN INC COM 46284V101 133,047 8,600 6.91 3,594 -6.89 0.0695
2015-11-13 2015-09-30 13F IRON MTN INC COM 46284V101 124,447 11,770 10.45 3,860 10.51 0.0773
2015-08-14 2015-06-30 13F IRON MTN INC COM 46284V101 112,677 13,130 13.19 3,493 -3.80 0.0646
2015-05-13 2015-03-31 13F IRON MTN INC COM 46284V101 99,547 9,510 10.56 3,631 1.91 0.0647
2015-02-13 2014-12-31 13F IRON MTN COM 462846106 90,037 68,457 317.22 3,563 405.39 0.0623
2014-11-14 2014-09-30 13F IRON MTN COM 462846106 21,580 5,600 35.04 705 24.56 0.0125
2014-08-14 2014-06-30 13F IRON MTN COM 462846106 15,980 -522 -3.16 566 24.40 0.0105
2014-05-14 2014-03-31 13F IRON MTN COM 462846106 16,502 580 3.64 455 -5.80 0.0083
2014-02-14 2013-12-31 13F IRON MTN COM 462846106 15,922 -2,227 -12.27 483 -1.43 0.0087
2013-11-13 2013-09-30 13F IRON MTN COM 462846106 18,149 0 0.00 490 1.45 0.0093
2013-08-13 2013-06-30 13F IRON MTN COM 462846106 18,149 18,149 483 0.0096
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.