Iron Mountain Incorporated
DE ˙ DB ˙ US46284V1017
111,85 € ↑2,30 (2,10%)
2026-06-05
DEL PRIS
SecurityDE:I5M / Iron Mountain Incorporated
InstitutionBlair William & Co/il
Latest Disclosed Ownership225,249 shares
Latest Disclosed Value $ 23,006,939
Blair William & Co/il ownership in I5M / Iron Mountain Incorporated

On May 8, 2026 - Blair William & Co/il filed a 13F-HR form disclosing ownership of 225,249 shares of Iron Mountain Incorporated (DE:I5M) valued at $19,997,606 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 238,285 shares of Iron Mountain Incorporated. This represents a change in shares of -5.47% during the quarter. The current value of the position is $25,194,101 USD.

Blair William & Co/il has a history of taking positions in derivatives of the underlying security (I5M) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

DE:I5M / Iron Mountain Incorporated Historical Put/Call Ratio
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)
2026-05-08 2026-03-31 13F IRON MTN INC DEL COM 46284V101 225,249 -13,036 -5.47 23,007 16.40 0.0659
2026-02-17 2025-12-31 13F IRON MTN INC DEL COM 46284V101 238,285 -80,125 -25.16 19,766 -39.11 0.0530
2025-11-12 2025-09-30 13F IRON MTN INC DEL COM 46284V101 318,410 4,280 1.36 32,459 0.74 0.0864
2025-07-24 2025-06-30 13F IRON MTN INC DEL COM 46284V101 314,130 -16,408 -4.96 32,220 13.30 0.0895
2025-05-09 2025-03-31 13F IRON MTN INC DEL COM 46284V101 330,538 -3,984 -1.19 28,440 -19.12 0.0858
2025-02-12 2024-12-31 13F IRON MTN INC DEL COM 46284V101 334,522 578 0.17 35,162 -11.39 0.1023
2024-11-12 2024-09-30 13F IRON MTN INC DEL COM 46284V101 333,944 -14,202 -4.08 39,683 27.19 0.1165
2024-08-12 2024-06-30 13F IRON MTN INC DEL COM 46284V101 348,146 -1,265 -0.36 31,201 11.33 0.0962
2024-05-09 2024-03-31 13F IRON MTN INC DEL COM 46284V101 349,411 10,326 3.05 28,026 18.11 0.0880
2024-02-12 2023-12-31 13F IRON MTN INC DEL COM 46284V101 339,085 -14,742 -4.17 23,729 12.81 0.0809
2023-11-09 2023-09-30 13F IRON MTN INC DEL COM 46284V101 353,827 1,176 0.33 21,035 4.98 0.0807
2023-08-11 2023-06-30 13F IRON MTN INC DEL COM 46284V101 352,651 -5,820 -1.62 20,038 5.65 0.0734
2023-05-12 2023-03-31 13F IRON MTN INC DEL COM 46284V101 358,471 -3,090 -0.85 18,967 5.23 0.0758
2023-02-10 2022-12-31 13F IRON MTN INC DEL COM 46284V101 361,561 4,716 1.32 18,024 14.87 0.0784
2022-11-09 2022-09-30 13F IRON MTN INC DEL COM 46284V101 356,845 82,162 29.91 15,690 17.32 0.0721
2022-08-10 2022-06-30 13F IRON MTN INC COM 46284V101 274,683 -3,580 -1.29 13,374 -13.26 0.0593
2022-05-13 2022-03-31 13F IRON MTN INC COM 46284V101 278,263 7,865 2.91 15,419 8.97 0.0540
2022-02-14 2021-12-31 13F IRON MTN INC COM 46284V101 270,398 6,190 2.34 14,150 23.26 0.0444
2021-11-12 2021-09-30 13F IRON MTN INC COM 46284V101 264,208 8,989 3.52 11,480 6.29 0.0391
2021-08-12 2021-06-30 13F IRON MTN INC COM 46284V101 255,219 -14,831 -5.49 10,801 8.06 0.0374
2021-05-13 2021-03-31 13F IRON MTN INC COM 46284V101 270,050 -62,431 -18.78 9,995 1.97 0.0377
2021-02-09 2020-12-31 13F IRON MTN INC COM 46284V101 332,481 13,225 4.14 9,802 14.60 0.0359
2020-11-06 2020-09-30 13F IRON MTN INC COM 46284V101 319,256 43,370 15.72 8,553 18.78 0.0363
2020-08-12 2020-06-30 13F IRON MTN INC COM 46284V101 275,886 -102,986 -27.18 7,201 -20.14 0.0343
2020-05-11 2020-03-31 13F IRON MTN INC COM 46284V101 378,872 6,525 1.75 9,017 -24.02 0.0564
2020-02-13 2019-12-31 13F IRON MTN INC COM 46284V101 372,347 -41,110 -9.94 11,867 -11.39 0.0610
2019-11-12 2019-09-30 13F IRON MTN INC COM 46284V101 413,457 -2,644 -0.64 13,392 2.83 0.0772
2019-08-13 2019-06-30 13F IRON MTN INC COM 46284V101 416,101 -6,800 -1.61 13,024 -13.15 0.0745
2019-05-14 2019-03-31 13F IRON MTN INC COM 46284V101 422,901 33,118 8.50 14,996 18.70 0.0914
2019-02-14 2018-12-31 13F IRON MTN INC COM 46284V101 389,783 1,072 0.28 12,633 -5.85 0.0923
2018-11-13 2018-09-30 13F IRON MTN INC COM 46284V101 388,711 14,668 3.92 13,418 2.47 0.0822
2018-08-13 2018-06-30 13F IRON MTN INC COM 46284V101 374,043 -196,468 -34.44 13,095 -30.15 0.0891
2018-05-15 2018-03-31 13F IRON MTN INC COM 46284V101 570,511 -293,856 -34.00 18,747 -42.52 0.1326
2018-02-14 2017-12-31 13F IRON MTN INC COM 46284V101 864,367 99,730 13.04 32,613 9.65 0.2214
2017-11-13 2017-09-30 13F IRON MOUNTAIN COM 46284V101 764,637 6,158 0.81 29,744 14.13 0.2230
2017-08-04 2017-06-30 13F IRON MOUNTAIN COM 46284V101 758,479 24,387 3.32 26,061 -1.88 0.1957
2017-05-10 2017-03-31 13F IRON MOUNTAIN COM 46284V101 734,092 -10,545 -1.42 26,561 9.82 0.2141
2017-02-14 2016-12-31 13F IRON MOUNTAIN COM 46284V101 744,637 -88,127 -10.58 24,186 -22.61 0.2163
2016-11-14 2016-09-30 13F IRON MOUNTAIN COM 46284V101 832,764 -63,026 -7.04 31,254 -12.40 0.2763
2016-08-08 2016-06-30 13F IRON MOUNTAIN COM 46284V101 895,790 -58,800 -6.16 35,679 10.22 0.3327
2016-05-16 2016-03-31 13F IRON MOUNTAIN COM 46284V101 954,590 -68 -0.01 32,370 25.54 0.3047
2016-02-16 2015-12-31 13F IRON MOUNTAIN COM 46284V101 954,658 64,755 7.28 25,784 -6.60 0.2421
2015-11-12 2015-09-30 13F IRON MOUNTAIN COM 46284V101 889,903 -33,835 -3.66 27,605 -3.60 0.2388
2015-08-03 2015-06-30 13F IRON MOUNTAIN COM 46284V101 923,738 57,550 6.64 28,635 -9.38 0.0428
2015-05-11 2015-03-31 13F IRON MOUNTAIN COM 46284V101 866,188 866,188 31,598 0.0486
2015-02-05 2014-12-31 13F IRON MOUNTAIN COM 462846106 0 -740,147 -100.00 0 -100.00
2014-11-04 2014-09-30 13F IRON MOUNTAIN COM 462846106 740,147 227,499 44.38 24,165 32.97 0.0413
2014-08-01 2014-06-30 13F IRON MOUNTAIN COM 462846106 512,648 -14,615 -2.77 18,173 25.02 0.0297
2014-05-06 2014-03-31 13F IRON MOUNTAIN COM 462846106 527,263 -19,922 -3.64 14,536 -12.47 0.0240
2014-02-11 2013-12-31 13F IRON MOUNTAIN COM 462846106 547,185 14,817 2.78 16,607 15.45 0.0274
2013-11-12 2013-09-30 13F IRON MOUNTAIN COM 462846106 532,368 22,597 4.43 14,384 6.04 0.0256
2013-08-07 2013-06-30 13F IRON MOUNTAIN COM 462846106 509,771 509,771 13,565 0.0268
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2017-05-10 2017-03-31 13F IRON MOUNTAIN OPTION Call 0 -100.00 0 -100.00 n/a n/a n/a
2017-02-14 2016-12-31 13F IRON MOUNTAIN OPTION Call 100 3 n/a n/a n/a
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.