Iron Mountain Incorporated
US ˙ NYSE ˙ US46284V1017

SecurityIRM / Iron Mountain Incorporated
InstitutionStifel Financial Corp
Latest Disclosed Ownership255,348 shares
Latest Disclosed Value $ 26,081,733
Stifel Financial Corp reports 12.37% increase in ownership of IRM / Iron Mountain Incorporated

On May 12, 2026 - Stifel Financial Corp filed a 13F-HR form disclosing ownership of 255,348 shares of Iron Mountain Incorporated (US:IRM) valued at $26,081,245 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 227,234 shares of Iron Mountain Incorporated. This represents a change in shares of 12.37% during the quarter. The current value of the position is $32,671,777 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.

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)
2026-05-12 2026-03-31 13F IRON MTN INC DEL COM 46284V101 255,348 28,114 12.37 26,082 38.37 0.0056
2026-02-13 2025-12-31 13F IRON MTN INC DEL COM 46284V101 227,234 9,097 4.17 18,849 -15.24 0.0170
2025-11-12 2025-09-30 13F IRON MTN INC DEL COM 46284V101 218,137 2,901 1.35 22,237 0.73 0.0203
2025-08-14 2025-06-30 13F IRON MTN INC DEL COM 46284V101 215,236 10,064 4.91 22,077 25.06 0.0215
2025-05-14 2025-03-31 13F IRON MTN INC DEL COM 46284V101 205,172 -64,662 -23.96 17,653 -37.76 0.0188
2025-02-13 2024-12-31 13F IRON MTN INC DEL COM 46284V101 269,834 -10,127 -3.62 28,363 -14.74 0.0295
2024-11-14 2024-09-30 13F IRON MTN INC DEL COM 46284V101 279,961 -106,556 -27.57 33,268 -3.96 0.0349
2024-08-13 2024-06-30 13F IRON MTN INC DEL COM 46284V101 386,517 -75,227 -16.29 34,640 -6.47 0.0390
2024-05-14 2024-03-31 13F IRON MTN INC DEL COM 46284V101 461,744 -15,869 -3.32 37,037 10.81 0.0422
2024-02-12 2023-12-31 13F IRON MTN INC DEL COM 46284V101 477,613 -5,906 -1.22 33,423 16.27 0.0421
2023-11-13 2023-09-30 13F IRON MTN INC DEL COM 46284V101 483,519 -32,848 -6.36 28,745 -2.03 0.0404
2023-08-14 2023-06-30 13F IRON MTN INC DEL COM 46284V101 516,367 -91,044 -14.99 29,340 -8.71 0.0401
2023-05-12 2023-03-31 13F IRON MTN INC DEL COM 46284V101 607,411 10,303 1.73 32,138 7.97 0.0461
2023-02-13 2022-12-31 13F IRON MTN INC DEL COM 46284V101 597,108 46,291 8.40 29,766 22.89 0.0447
2022-11-14 2022-09-30 13F IRON MTN INC DEL COM 46284V101 550,817 104,550 23.43 24,220 11.46 0.0397
2022-08-15 2022-06-30 13F IRON MTN INC COM 46284V101 446,267 -22,731 -4.85 21,729 -16.39 0.0340
2022-05-13 2022-03-31 13F IRON MTN INC COM 46284V101 468,998 -5,312 -1.12 25,988 4.71 0.0355
2022-02-14 2021-12-31 13F IRON MTN INC COM 46284V101 474,310 89,480 23.25 24,820 48.44 0.0328
2021-11-15 2021-09-30 13F IRON MTN INC COM 46284V101 384,830 96,031 33.25 16,721 36.81 0.0245
2021-08-13 2021-06-30 13F IRON MTN INC COM 46284V101 288,799 34,620 13.62 12,222 29.91 0.0183
2021-05-14 2021-03-31 13F IRON MTN INC COM 46284V101 254,179 -41,435 -14.02 9,408 7.96 0.0155
2021-02-12 2020-12-31 13F IRON MTN INC COM 46284V101 295,614 14,278 5.08 8,714 15.62 0.0155
2020-11-16 2020-09-30 13F IRON MTN INC COM 46284V101 281,336 -8,098 -2.80 7,537 -0.21 0.0155
2020-08-14 2020-06-30 13F IRON MTN INC COM 46284V101 289,434 -1,653,661 -85.10 7,553 -83.62 0.0174
2020-05-14 2020-03-31 13F IRON MTN INC COM 46284V101 1,943,095 -22,356 -1.14 46,102 -26.36 0.1273
2020-02-13 2019-12-31 13F IRON MTN INC COM 46284V101 1,965,451 -11,359 -0.57 62,607 -2.09 0.1304
2019-11-19 2019-09-30 13F/A-1 IRON MTN INC COM 46284V101 1,976,810 12,665 0.64 63,945 3.95 0.1631
2019-11-13 2019-09-30 13F IRON MTN INC COM 46284V101 1,892,943 -71,202 61,228 34,321.3629
2019-08-14 2019-06-30 13F IRON MTN INC COM 46284V101 1,964,145 9,510 0.49 61,516 -11.20 0.1586
2019-05-14 2019-03-31 13F IRON MTN INC COM 46284V101 1,954,635 13,712 0.71 69,276 10.13 0.1958
2019-02-13 2018-12-31 13F IRON MTN INC COM 46284V101 1,940,923 1,566,863 418.88 62,906 388.59 0.2034
2018-11-13 2018-09-30 13F IRON MTN INC COM 46284V101 374,060 22,847 6.51 12,875 4.12 0.0369
2018-08-14 2018-06-30 13F IRON MTN INC COM 46284V101 351,213 12,368 3.65 12,365 11.06 0.0379
2018-05-11 2018-03-31 13F IRON MTN INC COM 46284V101 338,845 50,455 17.50 11,134 2.25 0.0351
2018-02-14 2017-12-31 13F IRON MTN INC COM 46284V101 288,390 -37,235 -11.43 10,889 -14.10 0.0345
2017-11-13 2017-09-30 13F IRON MTN INC COM 46284V101 325,625 18,876 6.15 12,677 20.62 0.0440
2017-08-14 2017-06-30 13F IRON MTN INC COM 46284V101 306,749 166,346 118.48 10,510 109.32 0.0390
2017-05-10 2017-03-31 13F IRON MTN INC COM 46284V101 140,403 26,524 23.29 5,021 36.37 0.0194
2017-02-16 2016-12-31 13F IRON MTN INC COM 46284V101 113,879 28,348 33.14 3,682 14.92 0.0156
2016-11-15 2016-09-30 13F IRON MTN INC COM 46284V101 85,531 39,549 86.01 3,204 74.89 0.0144
2016-08-17 2016-06-30 13F IRON MTN INC COM 46284V101 45,982 45,982 0.00 1,832 0.0085
2016-05-16 2016-03-31 13F IRON MTN INC COM 46284V101 0 -48,657 -100.00 0 -100.00
2016-03-21 2015-12-31 13F/A-2 IRON MTN INC COM 46284V101 48,657 -1,001,573 -95.37 1,314 -95.97 0.0068
2016-02-26 2015-12-31 13F/A-1 IRON MTN INC COM 46284V101 47,681 -976 1,288 0.0067
2016-02-16 2015-12-31 13F IRON MTN INC COM 46284V101 41,312 2,534
2015-11-16 2015-09-30 13F IRON MTN INC COM 46284V101 1,050,230 180,129 20.70 32,577 20.78 0.1830
2015-08-17 2015-06-30 13F/A-1 IRON MTN INC COM 46284V101 870,101 -23,566 -2.64 26,973 -17.26 0.1394
2015-08-17 2015-06-30 13F IRON MTN INC COM 46284V101 870,063 26,972
2015-05-14 2015-03-31 13F IRON MTN INC COM 46284V101 893,667 861,309 2,661.81 32,601 2,506.00 0.1784
2015-02-13 2014-12-31 13F IRON MTN COM 462846106 32,358 845 2.68 1,251 21.57 0.0070
2014-11-13 2014-09-30 13F IRON MTN COM 462846106 31,513 13,198 72.06 1,029 58.55 0.0090
2014-08-14 2014-06-30 13F IRON MTN COM 462846106 18,315 436 2.44 649 31.64 0.0058
2014-05-15 2014-03-31 13F IRON MTN COM 462846106 17,879 17,879 493 0.0047
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.