Iron Mountain Incorporated
US ˙ NYSE ˙ US46284V1017

SecurityIRM / Iron Mountain Incorporated
InstitutionCitigroup Inc
Latest Disclosed Ownership315,634 shares
Latest Disclosed Value $ 32,238,901
Citigroup Inc ownership in IRM / Iron Mountain Incorporated

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 315,634 shares of Iron Mountain Incorporated (US:IRM) valued at $32,238,857 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 318,601 shares of Iron Mountain Incorporated. This represents a change in shares of -0.93% during the quarter. The current value of the position is $40,385,370 USD.

Citigroup Inc has a history of taking positions in derivatives of the underlying security (IRM) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD and put 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.

IRM / 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)
2026-05-11 2026-03-31 13F IRON MTN INC DEL COM 46284V101 315,634 -2,967 -0.93 32,239 21.99 0.0137
2026-02-13 2025-12-31 13F IRON MTN INC DEL COM 46284V101 318,601 -101,122 -24.09 26,428 -38.23 0.0117
2025-11-10 2025-09-30 13F IRON MTN INC DEL COM 46284V101 419,723 215,308 105.33 42,787 104.07 0.0191
2025-08-11 2025-06-30 13F IRON MTN INC DEL COM 46284V101 204,415 -26,214 -11.37 20,967 5.66 0.0103
2025-05-12 2025-03-31 13F IRON MTN INC DEL COM 46284V101 230,629 59,761 34.97 19,843 10.49 0.0101
2025-02-12 2024-12-31 13F IRON MTN INC DEL COM 46284V101 170,868 -97,521 -36.34 17,960 -43.69 0.0107
2024-11-12 2024-09-30 13F IRON MTN INC DEL COM 46284V101 268,389 20,905 8.45 31,893 43.79 0.0185
2024-08-12 2024-06-30 13F IRON MTN INC DEL COM 46284V101 247,484 11,386 4.82 22,180 17.12 0.0142
2024-05-10 2024-03-31 13F IRON MTN INC DEL COM 46284V101 236,098 78,677 49.98 18,937 71.90 0.0124
2024-02-09 2023-12-31 13F IRON MTN INC DEL COM 46284V101 157,421 -79,669 -33.60 11,016 -21.84 0.0078
2023-12-06 2023-09-30 13F/A-1 IRON MTN INC DEL COM 46284V101 237,090 11,911 5.29 14,095 10.17 0.0105
2023-11-09 2023-09-30 13F IRON MTN INC DEL COM 46284V101 237,090 11,911 14,095 0.0042
2023-08-10 2023-06-30 13F IRON MTN INC DEL COM 46284V101 225,179 -129,485 -36.51 12,795 -31.82 0.0084
2023-05-11 2023-03-31 13F IRON MTN INC DEL COM 46284V101 354,664 100,699 39.65 18,765 48.22 0.0132
2023-02-09 2022-12-31 13F IRON MTN INC DEL COM 46284V101 253,965 -140,645 -35.64 12,660 -27.03 0.0101
2022-11-10 2022-09-30 13F IRON MTN INC DEL COM 46284V101 394,610 108,368 37.86 17,350 24.49 0.0124
2022-08-10 2022-06-30 13F IRON MTN INC COM 46284V101 286,242 15,629 5.78 13,937 -7.05 0.0104
2022-05-12 2022-03-31 13F IRON MTN INC COM 46284V101 270,613 -74,704 -21.63 14,994 -17.02 0.0091
2022-02-10 2021-12-31 13F IRON MTN INC COM 46284V101 345,317 -137,287 -28.45 18,070 -13.83 0.0097
2021-11-10 2021-09-30 13F IRON MTN INC COM 46284V101 482,604 -257,597 -34.80 20,969 -33.06 0.0124
2021-08-10 2021-06-30 13F IRON MTN INC COM 46284V101 740,201 35,800 5.08 31,325 20.15 0.0189
2021-05-13 2021-03-31 13F IRON MTN INC COM 46284V101 704,401 226,731 47.47 26,071 85.12 0.0169
2021-02-11 2020-12-31 13F IRON MTN INC COM 46284V101 477,670 57,763 13.76 14,083 25.20 0.0083
2020-11-12 2020-09-30 13F IRON MTN INC COM 46284V101 419,907 157,286 59.89 11,248 64.11 0.0073
2020-08-12 2020-06-30 13F IRON MTN INC COM 46284V101 262,621 97,956 59.49 6,854 74.85 0.0053
2020-05-12 2020-03-31 13F IRON MTN INC COM 46284V101 164,665 -80,798 -32.92 3,920 -49.88 0.0035
2020-02-12 2019-12-31 13F IRON MTN INC COM 46284V101 245,463 -18,301 -6.94 7,822 -8.44 0.0057
2019-11-08 2019-09-30 13F IRON MTN INC COM 46284V101 263,764 -78,947 -23.04 8,543 -20.36 0.0068
2019-08-12 2019-06-30 13F IRON MTN INC COM 46284V101 342,711 110,157 47.37 10,727 30.07 0.0087
2019-05-13 2019-03-31 13F IRON MTN INC COM 46284V101 232,554 -8,062 -3.35 8,247 5.73 0.0079
2019-02-12 2018-12-31 13F IRON MTN INC COM 46284V101 240,616 193 0.08 7,800 -6.04 0.0079
2018-11-13 2018-09-30 13F IRON MTN INC COM 46284V101 240,423 36,975 18.17 8,301 16.54 0.0074
2018-08-10 2018-06-30 13F IRON MTN INC COM 46284V101 203,448 -31,572 -13.43 7,123 -7.76 0.0065
2018-05-11 2018-03-31 13F IRON MTN INC COM 46284V101 235,020 -21,088 -8.23 7,722 -20.09 0.0064
2018-02-12 2017-12-31 13F IRON MTN INC COM 46284V101 256,108 1,293 0.51 9,663 -2.51 0.0077
2017-11-13 2017-09-30 13F IRON MTN INC COM 46284V101 254,815 36,484 16.71 9,912 32.12 0.0081
2017-08-11 2017-06-30 13F IRON MTN INC COM 46284V101 218,331 54,262 33.07 7,502 28.20 0.0068
2017-05-12 2017-03-31 13F IRON MTN INC COM 46284V101 164,069 9,734 6.31 5,852 16.74 0.0052
2017-02-10 2016-12-31 13F IRON MTN INC COM 46284V101 154,335 75,631 96.10 5,013 69.70 0.0045
2016-11-10 2016-09-30 13F IRON MTN INC COM 46284V101 78,704 -11,775 -13.01 2,954 -18.01 0.0028
2016-08-12 2016-06-30 13F IRON MTN INC COM 46284V101 90,479 -10,955 -10.80 3,603 4.74 0.0037
2016-05-13 2016-03-31 13F IRON MTN INC COM 46284V101 101,434 36,649 56.57 3,440 96.57 0.0039
2016-02-12 2015-12-31 13F IRON MTN INC COM 46284V101 64,785 -147,313 -69.46 1,750 -73.40 0.0017
2015-11-13 2015-09-30 13F IRON MTN INC COM 46284V101 212,098 -10,252 -4.61 6,579 -4.56 0.0062
2015-08-13 2015-06-30 13F IRON MTN INC COM 46284V101 222,350 158,062 245.87 6,893 193.82 0.0061
2015-05-14 2015-03-31 13F IRON MTN INC COM 46284V101 64,288 41,604 183.41 2,346 167.50 0.0023
2015-02-17 2014-12-31 13F IRON MTN COM 462846106 22,684 -3,304 -12.71 877 3.42 0.0008
2014-11-14 2014-09-30 13F IRON MTN COM 462846106 25,988 -342,793 -92.95 848 -93.51 0.0007
2014-08-14 2014-06-30 13F IRON MTN COM 462846106 368,781 195,512 112.84 13,073 173.72 0.0125
2014-05-15 2014-03-31 13F IRON MTN COM 462846106 173,269 -64,285 -27.06 4,776 -33.76 0.0049
2014-02-14 2013-12-31 13F IRON MTN COM 462846106 237,554 -119,736 -33.51 7,210 -25.32 0.0065
2013-11-14 2013-09-30 13F IRON MTN COM 462846106 357,290 166,490 87.26 9,654 90.15 0.0090
2013-08-14 2013-06-30 13F IRON MTN COM 462846106 190,800 190,800 5,077 0.0050
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
(%)
2021-05-13 2021-03-31 13F IRON MTN INC COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2021-02-11 2020-12-31 13F IRON MTN INC COM Call 67,200 -36.30 1,981 -29.93 n/a n/a n/a
2020-11-12 2020-09-30 13F IRON MTN INC COM Call 105,500 -17.51 2,827 -15.31 n/a n/a n/a
2020-08-12 2020-06-30 13F IRON MTN INC COM Call 127,900 -7.45 3,338 1.49 n/a n/a n/a
2020-05-12 2020-03-31 13F IRON MTN INC COM Call 138,200 5.02 3,289 -21.58 n/a n/a n/a
2020-02-12 2019-12-31 13F IRON MTN INC COM Call 131,600 9.94 4,194 8.18 n/a n/a n/a
2019-11-08 2019-09-30 13F IRON MTN INC COM Call 119,700 -21.20 3,877 -18.45 n/a n/a n/a
2019-08-12 2019-06-30 13F IRON MTN INC COM Call 151,900 195.53 4,754 160.92 n/a n/a n/a
2019-05-13 2019-03-31 13F IRON MTN INC COM Call 51,400 211.52 1,822 240.56 n/a n/a n/a
2019-02-12 2018-12-31 13F IRON MTN INC COM Call 16,500 6.45 535 0.00 n/a n/a n/a
2018-11-13 2018-09-30 13F IRON MTN INC COM Call 15,500 -4.91 535 -6.30 n/a n/a n/a
2018-08-10 2018-06-30 13F IRON MTN INC COM Call 16,300 26.36 571 34.67 n/a n/a n/a
2018-05-11 2018-03-31 13F IRON MTN INC COM Call 12,900 -33.51 424 -42.08 n/a n/a n/a
2018-02-12 2017-12-31 13F IRON MTN INC COM Call 19,400 -67.01 732 -67.99 n/a n/a n/a
2017-11-13 2017-09-30 13F IRON MTN INC COM Call 58,800 345.45 2,287 403.74 n/a n/a n/a
2017-08-11 2017-06-30 13F IRON MTN INC COM Call 13,200 528.57 454 505.33 n/a n/a n/a
2017-05-12 2017-03-31 13F IRON MTN INC COM Call 2,100 -43.24 75 -37.50 n/a n/a n/a
2017-02-10 2016-12-31 13F IRON MTN INC COM Call 3,700 -22.92 120 -33.33 n/a n/a n/a
2016-11-10 2016-09-30 13F IRON MTN INC COM Call 4,800 -25.23 180 -29.69 n/a n/a n/a
2016-08-12 2016-06-30 13F IRON MTN INC COM Call 6,420 -89.67 256 -87.84 n/a n/a n/a
2016-05-13 2016-03-31 13F IRON MTN INC COM Call 62,120 -93.89 2,106 -92.33 n/a n/a n/a
2016-02-12 2015-12-31 13F IRON MTN INC COM Call 1,017,140 23.46 27,473 7.50 n/a n/a n/a
2015-11-13 2015-09-30 13F IRON MTN INC COM Call 823,840 0.49 25,556 0.56 n/a n/a n/a
2015-08-13 2015-06-30 13F IRON MTN INC COM Call 819,810 17,379.96 25,414 14,761.99 n/a n/a n/a
2015-05-14 2015-03-31 13F IRON MTN INC COM Call 4,690 171 n/a n/a n/a
2014-08-14 2014-06-30 13F IRON MTN COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2014-05-15 2014-03-31 13F IRON MTN COM Call 196,200 143.42 5,409 121.14 n/a n/a n/a
2014-02-14 2013-12-31 13F IRON MTN COM Call 80,600 101.50 2,446 126.27 n/a n/a n/a
2013-11-14 2013-09-30 13F IRON MTN COM Call 40,000 300.00 1,081 306.39 n/a n/a n/a
2013-08-14 2013-06-30 13F IRON MTN COM Call 10,000 266 n/a n/a n/a
Disclosed Put 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
(%)
2021-11-10 2021-09-30 13F IRON MTN INC COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-08-10 2021-06-30 13F IRON MTN INC COM Put 100,000 0.00 4,232 14.35 n/a n/a n/a
2021-05-13 2021-03-31 13F IRON MTN INC COM Put 100,000 -17.08 3,701 4.11 n/a n/a n/a
2021-02-11 2020-12-31 13F IRON MTN INC COM Put 120,600 1.26 3,555 11.41 n/a n/a n/a
2020-11-12 2020-09-30 13F IRON MTN INC COM Put 119,100 -21.75 3,191 -19.66 n/a n/a n/a
2020-08-12 2020-06-30 13F IRON MTN INC COM Put 152,200 70.44 3,972 86.92 n/a n/a n/a
2020-05-12 2020-03-31 13F IRON MTN INC COM Put 89,300 -17.62 2,125 -38.48 n/a n/a n/a
2020-02-12 2019-12-31 13F IRON MTN INC COM Put 108,400 -11.80 3,454 -13.22 n/a n/a n/a
2019-11-08 2019-09-30 13F IRON MTN INC COM Put 122,900 53.05 3,980 58.38 n/a n/a n/a
2019-08-12 2019-06-30 13F IRON MTN INC COM Put 80,300 66.94 2,513 47.39 n/a n/a n/a
2019-05-13 2019-03-31 13F IRON MTN INC COM Put 48,100 968.89 1,705 1,067.81 n/a n/a n/a
2019-02-12 2018-12-31 13F IRON MTN INC COM Put 4,500 -28.57 146 -32.72 n/a n/a n/a
2018-11-13 2018-09-30 13F IRON MTN INC COM Put 6,300 -60.38 217 -61.04 n/a n/a n/a
2018-08-10 2018-06-30 13F IRON MTN INC COM Put 15,900 93.90 557 107.06 n/a n/a n/a
2018-05-11 2018-03-31 13F IRON MTN INC COM Put 8,200 -13.68 269 -24.86 n/a n/a n/a
2018-02-12 2017-12-31 13F IRON MTN INC COM Put 9,500 196.88 358 188.71 n/a n/a n/a
2017-11-13 2017-09-30 13F IRON MTN INC COM Put 3,200 -28.89 124 -20.00 n/a n/a n/a
2017-08-11 2017-06-30 13F IRON MTN INC COM Put 4,500 21.62 155 17.42 n/a n/a n/a
2017-05-12 2017-03-31 13F IRON MTN INC COM Put 3,700 -32.36 132 -25.84 n/a n/a n/a
2017-02-10 2016-12-31 13F IRON MTN INC COM Put 5,470 1.86 178 -11.88 n/a n/a n/a
2016-11-10 2016-09-30 13F IRON MTN INC COM Put 5,370 -98.35 202 -98.45 n/a n/a n/a
2016-08-12 2016-06-30 13F IRON MTN INC COM Put 326,370 -53.34 12,999 -45.20 n/a n/a n/a
2016-05-13 2016-03-31 13F IRON MTN INC COM Put 699,470 67.51 23,719 110.29 n/a n/a n/a
2016-02-12 2015-12-31 13F IRON MTN INC COM Put 417,570 1,990.99 11,279 1,722.13 n/a n/a n/a
2015-11-13 2015-09-30 13F IRON MTN INC COM Put 19,970 2.04 619 1.98 n/a n/a n/a
2015-08-13 2015-06-30 13F IRON MTN INC COM Put 19,570 249.46 607 197.55 n/a n/a n/a
2015-05-14 2015-03-31 13F IRON MTN INC COM Put 5,600 -83.03 204 -84.01 n/a n/a n/a
2015-02-17 2014-12-31 13F IRON MTN COM Put 33,000 0.00 1,276 18.48 n/a n/a n/a
2014-11-14 2014-09-30 13F IRON MTN COM Put 33,000 1,077 n/a n/a n/a
2014-08-14 2014-06-30 13F IRON MTN COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2014-05-15 2014-03-31 13F IRON MTN COM Put 11,300 -96.94 312 -97.21 n/a n/a n/a
2014-02-14 2013-12-31 13F IRON MTN COM Put 368,800 1,117.16 11,193 1,266.67 n/a n/a n/a
2013-11-14 2013-09-30 13F IRON MTN COM Put 30,300 -65.72 819 -65.18 n/a n/a n/a
2013-08-14 2013-06-30 13F IRON MTN COM Put 88,400 2,352 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.