Iron Mountain Incorporated
US ˙ NYSE ˙ US46284V1017

SecurityIRM / Iron Mountain Incorporated
InstitutionNatixis Advisors, L.p.
Latest Disclosed Ownership166,136 shares
Latest Disclosed Value $ 16,969
Natixis Advisors, L.p. reports 18.32% increase in ownership of IRM / Iron Mountain Incorporated

On May 13, 2026 - Natixis Advisors, L.p. filed a 13F-HR form disclosing ownership of 166,136 shares of Iron Mountain Incorporated (US:IRM) valued at $16,969,131 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 10, 2026 disclosing 140,414 shares of Iron Mountain Incorporated. This represents a change in shares of 18.32% during the quarter. The current value of the position is $21,257,101 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)
2026-05-13 2026-03-31 13F IRON MTN INC DEL COM 46284V101 166,136 25,722 18.32 17 45.45 0.0236
2026-02-10 2025-12-31 13F IRON MTN INC DEL COM 46284V101 140,414 -32,538 -18.81 12 -35.29 0.0165
2025-11-13 2025-09-30 13F IRON MTN INC DEL COM 46284V101 172,952 -6,911 -3.84 18 -5.56 0.0257
2025-08-13 2025-06-30 13F IRON MTN INC DEL COM 46284V101 179,863 12,035 7.17 18 28.57 0.0293
2025-05-08 2025-03-31 13F IRON MTN INC DEL COM 46284V101 167,828 -32,686 -16.30 14 -33.33 0.0267
2025-02-10 2024-12-31 13F IRON MTN INC DEL COM 46284V101 200,514 -1,060 -0.53 21 -8.70 0.0394
2024-11-06 2024-09-30 13F IRON MTN COM 46284V101 201,574 -9,402 -4.46 24 27.78 0.0467
2024-08-01 2024-06-30 13F IRON MTN INC DEL COM 46284V101 210,976 44,228 26.52 19 38.46 0.0411
2024-04-25 2024-03-31 13F IRON MTN INC DEL COM 46284V101 166,748 3,453 2.11 13 18.18 0.0308
2024-02-06 2023-12-31 13F IRON MTN INC DEL COM 46284V101 163,295 5,219 3.30 11 22.22 0.0301
2023-11-13 2023-09-30 13F IRON MTN INC DEL COM 46284V101 158,076 22,816 16.87 9 28.57 0.0287
2023-08-15 2023-06-30 13F IRON MTN INC DEL COM 46284V101 135,260 -124 -0.09 8 0.00 0.0237
2023-05-11 2023-03-31 13F IRON MTN INC DEL COM 46284V101 135,384 5,385 4.14 7 16.67 0.0247
2023-01-27 2022-12-31 13F IRON MTN INC DEL COM COM 46284V101 129,999 4,710 3.76 6 -99.89 0.0245
2022-11-14 2022-09-30 13F IRON MOUNTAIN COM 46284V101 125,289 7,920 6.75 5,509 -3.60 0.0233
2022-08-12 2022-06-30 13F IRON MTN COM 46284V101 117,369 -10,206 -8.00 5,715 -19.15 0.0251
2022-05-12 2022-03-31 13F IRON MTN COM 46284V101 127,575 10,231 8.72 7,069 15.11 0.0270
2022-02-08 2021-12-31 13F IRON MTN COM 46284V101 117,344 7,190 6.53 6,141 28.31 0.0235
2021-11-15 2021-09-30 13F IRON MTN INC NEW COM COM 46284V101 110,154 11,439 11.59 4,786 14.55 0.0197
2021-08-12 2021-06-30 13F IRON MTN COM 46284V101 98,715 5,871 6.32 4,178 21.59 0.0195
2021-05-05 2021-03-31 13F IRON MTN COM 46284V101 92,844 4,519 5.12 3,436 31.95 0.0179
2021-02-12 2020-12-31 13F IRON MTN COM 46284V101 88,325 11,271 14.63 2,604 26.16 0.0150
2020-11-12 2020-09-30 13F IRON MTN COM 46284V101 77,054 11,718 17.93 2,064 21.06 0.0130
2020-08-11 2020-06-30 13F IRON MTN COM 46284V101 65,336 -15,890 -19.56 1,705 -11.80 0.0113
2020-04-27 2020-03-31 13F IRON MTN COM 46284V101 81,226 15,388 23.37 1,933 -7.86 0.0158
2020-02-10 2019-12-31 13F IRON MTN COM 46284V101 65,838 10,087 18.09 2,098 16.17 0.0148
2019-11-12 2019-09-30 13F IRON MOUNTAIN COM 46284V101 55,751 -866 -1.53 1,806 1.92 0.0143
2019-08-12 2019-06-30 13F IRON MOUNTAIN COM 46284V101 56,617 -6,093 -9.72 1,772 -20.32 0.0145
2019-05-15 2019-03-31 13F/A-1 IRON MOUNTAIN COM 46284V101 62,710 -8,736 -12.23 2,224 -3.97 0.0195
2019-05-15 2019-03-31 13F IRON MOUNTAIN COM 46284V101 62,710 -8,736 2,224
2019-02-13 2018-12-31 13F/A-1 IRON MTN COM 46284V101 71,446 20,123 39.21 2,316 30.77 0.0229
2019-02-13 2018-12-31 13F IRON MTN COM 46284V101 71,446 20,123 2,316
2018-11-13 2018-09-30 13F IRON MTN COM 46284V101 51,323 361 0.71 1,771 -0.73 0.0156
2018-08-14 2018-06-30 13F/A-1 IRON MTN COM 46284V101 50,962 2,487 5.13 1,784 11.99 0.0170
2018-08-14 2018-06-30 13F IRON MTN COM 46284V101 50,962 1,784
2018-05-10 2018-03-31 13F IRON MTN COM 46284V101 48,475 194 0.40 1,593 -12.57 0.0157
2018-02-14 2017-12-31 13F IRON MTN COM 46284V101 48,281 2,240 4.87 1,822 1.73 0.0186
2017-11-14 2017-09-30 13F IRON MTN INC COM 46284V101 46,041 629 1.39 1,791 14.81 0.0189
2017-07-27 2017-06-30 13F IRON MTN COM 46284V101 45,412 -140 -0.31 1,560 -4.00 0.0169
2017-05-12 2017-03-31 13F IRON MTN COM 46284V101 45,552 6,266 15.95 1,625 27.35 0.0180
2017-02-07 2016-12-31 13F IRON MTN COM 46284V101 39,286 -2,830 -6.72 1,276 -19.29 0.0153
2016-11-04 2016-09-30 13F IRON MTN COM 46284V101 42,116 -2,226 -5.02 1,581 -10.48 0.0205
2016-08-01 2016-06-30 13F IRON MTN COM 46284V101 44,342 7,741 21.15 1,766 42.30 0.0244
2016-05-06 2016-03-31 13F IRON MTN COM 46284V101 36,601 9,153 33.35 1,241 67.48 0.0186
2016-02-12 2015-12-31 13F IRON MTN COM 46284V101 27,448 -4,100 -13.00 741 -24.31 0.0121
2015-11-12 2015-09-30 13F IRON MTN COM 46284V101 31,548 3,147 11.08 979 11.25 0.0170
2015-08-14 2015-06-30 13F IRON MTN COM 46284V101 28,401 -9,321 -24.71 880 -36.05 0.0149
2015-05-15 2015-03-31 13F IRON MTN COM 46284V101 37,722 24,656 188.70 1,376 172.48 0.0242
2015-02-05 2014-12-31 13F IRON MTN COM 462846106 13,066 2,584 24.65 505 47.66 0.0095
2014-11-03 2014-09-30 13F IRON MTN COM 462846106 10,482 113 1.09 342 -7.07 0.0069
2014-08-13 2014-06-30 13F IRON MTN COM 462846106 10,369 -15,852 -60.46 368 -48.10 0.0053
2013-10-30 2013-09-30 13F IRON MTN COM 462846106 26,221 -138,573 -84.09 709 -83.83 0.0131
2013-07-19 2013-06-30 13F IRON MTN COM 462846106 164,794 164,794 4,385 0.0874
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.