Iron Mountain Incorporated
US ˙ NYSE ˙ US46284V1017

SecurityIRM / Iron Mountain Incorporated
InstitutionChicago Capital, LLC
Latest Disclosed Ownership83,951 shares
Latest Disclosed Value $ 8,574,755
Chicago Capital, LLC reports 0.95% increase in ownership of IRM / Iron Mountain Incorporated

On April 23, 2026 - Chicago Capital, LLC filed a 13F-HR form disclosing ownership of 83,951 shares of Iron Mountain Incorporated (US:IRM) valued at $8,574,755 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 26, 2026 disclosing 83,162 shares of Iron Mountain Incorporated. This represents a change in shares of 0.95% during the quarter. The current value of the position is $10,741,530 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)
2026-04-23 2026-03-31 13F IRON MTN INC DEL COM 46284V101 83,951 789 0.95 8,575 24.30 0.2312
2026-01-26 2025-12-31 13F IRON MTN INC DEL COM 46284V101 83,162 -854 -1.02 6,898 -19.45 0.1704
2025-10-22 2025-09-30 13F IRON MTN INC DEL COM 46284V101 84,016 -13,620 -13.95 8,565 -14.48 0.2108
2025-07-17 2025-06-30 13F IRON MTN INC DEL COM 46284V101 97,636 -1,578 -1.59 10,014 17.31 0.2471
2025-04-17 2025-03-31 13F IRON MTN INC DEL COM 46284V101 99,214 -3,863 -3.75 8,536 -21.21 0.2411
2025-01-24 2024-12-31 13F IRON MTN INC DEL COM 46284V101 103,077 24 0.02 10,834 -11.52 0.2873
2024-10-18 2024-09-30 13F IRON MTN INC DEL COM 46284V101 103,053 17,961 21.11 12,246 60.59 0.3401
2024-08-06 2024-06-30 13F IRON MTN INC DEL COM 46284V101 85,092 -940 -1.09 7,626 10.51 0.2267
2024-04-15 2024-03-31 13F IRON MTN INC DEL COM 46284V101 86,032 -490 -0.57 6,901 13.97 0.2103
2024-01-22 2023-12-31 13F IRON MTN INC DEL COM 46284V101 86,522 -5,634 -6.11 6,055 10.51 0.2180
2023-10-25 2023-09-30 13F IRON MTN INC DEL COM 46284V101 92,156 0 0.00 5,479 4.62 0.2563
2023-07-20 2023-06-30 13F IRON MTN INC DEL COM 46284V101 92,156 0 0.00 5,236 7.41 0.2361
2023-04-18 2023-03-31 13F IRON MTN INC DEL COM 46284V101 92,156 0 0.00 4,876 6.14 0.2426
2023-01-20 2022-12-31 13F IRON MTN INC DEL COM 46284V101 92,156 0 0.00 4,594 13.35 0.2541
2022-10-14 2022-09-30 13F IRON MTN INC DEL COM 46284V101 92,156 -300 -0.32 4,052 -10.00 0.2344
2022-07-21 2022-06-30 13F IRON MTN INC COM 46284V101 92,456 -473 -0.51 4,502 -12.57 0.2487
2022-04-21 2022-03-31 13F IRON MTN INC COM 46284V101 92,929 -536 -0.57 5,149 5.27 0.2216
2022-01-20 2021-12-31 13F IRON MTN INC COM 46284V101 93,465 0 0.00 4,891 20.44 0.1821
2021-10-28 2021-09-30 13F IRON MTN INC COM 46284V101 93,465 -24 -0.03 4,061 2.65 0.1540
2021-07-22 2021-06-30 13F IRON MTN INC COM 46284V101 93,489 -927 -0.98 3,956 13.22 0.1546
2021-04-13 2021-03-31 13F IRON MTN INC COM 46284V101 94,416 -2,404 -2.48 3,494 22.42 0.1475
2021-01-25 2020-12-31 13F IRON MTN INC COM 46284V101 96,820 -2,792 -2.80 2,854 6.93 0.1275
2020-10-13 2020-09-30 13F IRON MTN INC COM 46284V101 99,612 -11,306 -10.19 2,669 -7.81 0.1372
2020-07-29 2020-06-30 13F IRON MTN INC COM 46284V101 110,918 -434,645 -79.67 2,895 -77.70 0.1678
2020-04-21 2020-03-31 13F IRON MTN INC COM 46284V101 545,563 -112,275 -17.07 12,984 -38.07 1.0470
2020-01-14 2019-12-31 13F IRON MTN INC COM 46284V101 657,838 -236,893 -26.48 20,965 -27.66 1.2791
2019-10-28 2019-09-30 13F IRON MOUNTAIN COMMON 46284V101 894,731 237 0.03 28,980 3.51 1.9409
2019-07-11 2019-06-30 13F IRON MOUNTAIN COMMON 46284V101 894,494 13,997 1.59 27,998 -10.33 1.7911
2019-04-23 2019-03-31 13F IRON MOUNTAIN INC NPV COMMON 46284V101 880,497 45,951 5.51 31,222 15.43 2.1223
2019-02-11 2018-12-31 13F IRON MOUNTAIN INC NPV COM 46284V101 834,546 -33,107 -3.82 27,048 -9.69 2.2056
2018-11-02 2018-09-30 13F IRON MOUNTAIN INC NPV COM 46284V101 867,653 90,488 11.64 29,951 10.08 2.0720
2018-07-19 2018-06-30 13F IRON MOUNTAIN INC NPV COM 46284V101 777,165 426,848 121.85 27,209 136.37 2.1937
2018-05-09 2018-03-31 13F Iron Mountain Inc Npv COM 46284V101 350,317 350,317 11,511 1.5360
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.