Latest Period
Q4 2025
Security Snapshot
IRON MOUNTAIN INC - Common Stock (IRM) Institutional Ownership
CUSIP: 46284V101
13F Institutional Holders and Ownership History from Q1 2014 to Q1 2026
Institutions Reporting
995
Shares (Excl. Options)
257,003,232
Price
$82.95
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- Type / Class
- Equity / Common Stock
- Symbol
- IRM on NYSE
- Shares outstanding
- 297,582,354
- Price per share
- $103.30
- All holders as of 31 Dec 2025
- Q4 2025
- Total 13F shares
- 257,003,232
- Total reported value
- $21,331,287,430
- % of total 13F portfolios
- 0.01%
- Share change
- +6,510,924
- Value change
- +$504,156,459
- Number of holders
- 995
- Price from insider filings
- $103.30
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors
Quick Takeaways
- IRM - IRON MOUNTAIN INC - Common Stock is tracked under CUSIP 46284V101.
- 995 institutions reported positions in Q4 2025.
- 3 significant owners is listed from Schedule 13D/13G reporting.
What Changed
- Holder count moved from 995 to 409 between Q4 2025 and Q1 2026.
- Reported value moved from $21,331,287,430 to $1,660,926,228.
Why This Matters
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Source Evidence
Source: SEC Form 13F
Open SEC Evidence
Latest holder context comes from 995 institutions filings for Q4 2025.
Investment Quick Answers
What is CUSIP 46284V101?
CUSIP 46284V101 identifies IRM - IRON MOUNTAIN INC - Common Stock in SEC 13F datasets.
Where can I see the latest institutional holders?
Review the Q4 2025 holders report and the ownership history table below.
Next ownership checks
Use the next link that matches the question you still need to answer about this security.
- Latest 13F filings when you want to inspect fresh institutional portfolio moves.
- Latest Schedule 13D/13G reports when you need large-owner changes outside the 13F cycle.
- All institutional ownership pages to compare this security with other holder-history pages.
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 46284V101:
Significant Owners of IRON MOUNTAIN INC - Common Stock (IRM) based on Schedule 13D/G filings
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| VANGUARD PORTFOLIO MANAGEMENT LLC | 8.4% | $2,558,722,929 | 25,051,135 | Vanguard Portfolio Management | 31 Mar 2026 | |||
| VANGUARD CAPITAL MANAGEMENT LLC | 7.4% | $2,234,037,028 | 21,872,303 | Vanguard Capital Management | 31 Mar 2026 | |||
| COHEN & STEERS, INC. | 6.5% | +21% | $1,704,112,303 | +$274,399,992 | 19,106,540 | +19% | Cohen & Steers, Inc. | 31 Dec 2025 |
As of 31 Dec 2025, 995 institutional investors reported holding 257,003,232 shares of IRON MOUNTAIN INC - Common Stock (IRM). This represents 86% of the company’s total 297,582,354 outstanding shares.
Top 25 Institutional Shareholders
The largest institutional shareholders of IRON MOUNTAIN INC - Common Stock (IRM) together control 64% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| VANGUARD GROUP INC | 16% | 46,627,483 | -1.3% | 0.06% | $3,867,749,715 |
| BlackRock, Inc. | 11% | 32,919,658 | +3.8% | 0.05% | $2,730,685,613 |
| COHEN & STEERS, INC. | 6.4% | 18,903,716 | +20% | 2.8% | $1,568,110,000 |
| STATE STREET CORP | 5.7% | 16,888,798 | -1.4% | 0.05% | $1,415,001,718 |
| GEODE CAPITAL MANAGEMENT, LLC | 2.8% | 8,292,653 | +1.2% | 0.04% | $685,374,233 |
| FMR LLC | 2.7% | 7,984,304 | +1.6% | 0.03% | $662,298,027 |
| NORGES BANK | 1.5% | 4,447,133 | 0.04% | $368,889,682 | |
| DIMENSIONAL FUND ADVISORS LP | 1.5% | 4,429,359 | +1.9% | 0.08% | $367,418,097 |
| Invesco Ltd. | 1.5% | 4,417,367 | -13% | 0.06% | $366,420,630 |
| PRINCIPAL FINANCIAL GROUP INC | 1.4% | 4,207,596 | +66% | 0.18% | $349,020,857 |
| NORTHERN TRUST CORP | 1.4% | 4,152,569 | +3% | 0.04% | $344,455,599 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 1.3% | 3,880,275 | +5.6% | 0.05% | $321,868,811 |
| Daiwa Securities Group Inc. | 1.2% | 3,654,086 | +16% | 0.98% | $303,106,000 |
| MORGAN STANLEY | 1.2% | 3,598,972 | -0.34% | 0.02% | $298,534,860 |
| Legal & General Group Plc | 1.1% | 3,356,420 | +4.4% | 0.06% | $278,415,040 |
| Contour Asset Management LLC | 0.95% | 2,832,182 | -11% | 5.5% | $234,929,497 |
| CENTERSQUARE INVESTMENT MANAGEMENT LLC | 0.88% | 2,631,453 | +4.7% | 2.2% | $218,279,027 |
| DEUTSCHE BANK AG\ | 0.85% | 2,541,992 | -12% | 0.07% | $210,858,237 |
| PRUDENTIAL FINANCIAL INC | 0.78% | 2,310,481 | +9.3% | 0.23% | $191,654,398 |
| Pictet Asset Management Holding SA | 0.77% | 2,295,965 | -6.8% | 0.18% | $190,433,581 |
| Nuveen, LLC | 0.72% | 2,127,931 | -0.68% | 0.05% | $176,511,876 |
| Capital World Investors | 0.71% | 2,117,169 | 0% | 0.02% | $175,619,169 |
| JPMORGAN CHASE & CO | 0.65% | 1,927,935 | -6.2% | 0.01% | $159,922,241 |
| AMERIPRISE FINANCIAL INC | 0.59% | 1,744,405 | +2.2% | 0.03% | $142,472,791 |
| Vontobel Holding Ltd. | 0.57% | 1,689,246 | +57% | 0.46% | $140,122,956 |
Institutional Holders of IRON MOUNTAIN INC - Common Stock (IRM) across Reporting Periods
| Period | Reported Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 16,262,748 | $1,660,926,228 | -$141,006,718 | $102.14 | 409 |
| 2025 Q4 | 257,003,232 | $21,331,287,430 | +$504,156,459 | $82.95 | 995 |
| 2025 Q3 | 250,099,173 | $25,501,731,178 | +$119,529,096 | $101.94 | 1,008 |
| 2025 Q2 | 248,525,285 | $25,494,373,784 | +$803,176,666 | $102.57 | 1,032 |
| 2025 Q1 | 240,934,690 | $20,734,604,323 | +$263,720,115 | $86.04 | 981 |
| 2024 Q4 | 236,810,872 | $24,896,739,978 | -$607,469,785 | $105.11 | 1,052 |
| 2024 Q3 | 241,814,752 | $28,741,204,354 | -$1,107,026,346 | $118.83 | 1,044 |
| 2024 Q2 | 247,404,957 | $22,194,271,901 | +$1,038,973,385 | $89.62 | 958 |
| 2024 Q1 | 236,401,763 | $18,948,590,587 | +$213,667,716 | $80.21 | 929 |
| 2023 Q4 | 233,491,997 | $16,340,519,763 | +$271,706,582 | $69.98 | 884 |
| 2023 Q3 | 229,526,142 | $13,658,760,340 | +$171,582,469 | $59.45 | 826 |
| 2023 Q2 | 226,655,213 | $12,884,186,843 | +$83,715,858 | $56.82 | 805 |
| 2023 Q1 | 224,502,203 | $11,873,411,821 | -$142,387,662 | $52.91 | 778 |
| 2022 Q4 | 227,868,373 | $11,377,567,891 | +$44,555,254 | $49.85 | 773 |
| 2022 Q3 | 226,777,832 | $9,985,042,681 | +$96,567,031 | $43.97 | 731 |
| 2022 Q2 | 224,032,661 | $10,915,712,274 | -$16,300,595 | $48.69 | 755 |
| 2022 Q1 | 224,442,000 | $12,439,113,556 | -$172,066,245 | $55.41 | 765 |
| 2021 Q4 | 227,876,068 | $11,926,247,380 | -$32,879,189 | $52.33 | 735 |
| 2021 Q3 | 228,189,194 | $9,924,915,322 | -$6,524,012 | $43.45 | 693 |
| 2021 Q2 | 228,564,720 | $9,682,737,503 | +$46,970,021 | $42.32 | 674 |
| 2021 Q1 | 227,132,792 | $8,414,631,609 | -$145,818,371 | $37.01 | 611 |
| 2020 Q4 | 231,708,448 | $6,837,063,849 | -$283,592,825 | $29.48 | 591 |
| 2020 Q3 | 242,359,753 | $6,501,463,965 | -$98,472,508 | $26.79 | 576 |
| 2020 Q2 | 245,858,050 | $6,425,333,738 | +$15,126,586 | $26.10 | 547 |
| 2020 Q1 | 245,777,190 | $5,859,389,592 | +$68,100,447 | $23.80 | 512 |
| 2019 Q4 | 241,595,064 | $7,707,843,802 | -$27,134,818 | $31.87 | 559 |
| 2019 Q3 | 241,931,210 | $7,843,810,763 | -$246,220,322 | $32.39 | 497 |
| 2019 Q2 | 249,642,605 | $7,818,448,769 | -$130,825,562 | $31.30 | 504 |
| 2019 Q1 | 255,112,254 | $9,053,075,767 | -$60,152,842 | $35.46 | 521 |
| 2018 Q4 | 256,785,444 | $8,329,106,421 | +$108,888,980 | $32.41 | 471 |
| 2018 Q3 | 254,786,080 | $8,794,156,030 | +$164,726,049 | $34.52 | 490 |
| 2018 Q2 | 249,978,232 | $8,751,026,653 | -$52,174,184 | $35.01 | 473 |
| 2018 Q1 | 251,290,445 | $8,257,335,630 | -$240,670,445 | $32.86 | 461 |
| 2017 Q4 | 253,727,143 | $9,572,639,775 | +$596,685,256 | $37.73 | 466 |
| 2017 Q3 | 237,544,010 | $9,239,995,794 | +$222,791,449 | $38.90 | 402 |
| 2017 Q2 | 231,677,828 | $7,960,574,117 | +$112,214,924 | $34.36 | 374 |
| 2017 Q1 | 228,349,330 | $8,132,878,979 | +$977,679,165 | $35.67 | 363 |
| 2016 Q4 | 218,034,820 | $7,082,236,440 | +$22,178,609 | $32.48 | 363 |
| 2016 Q3 | 216,105,007 | $8,106,627,841 | +$99,287,383 | $37.53 | 366 |
| 2016 Q2 | 214,339,014 | $8,533,031,123 | +$470,432,632 | $39.83 | 376 |
| 2016 Q1 | 202,754,255 | $6,873,479,222 | +$16,388,073 | $33.91 | 336 |
| 2015 Q4 | 203,513,181 | $5,498,119,514 | -$53,702,658 | $27.01 | 328 |
| 2015 Q3 | 205,327,999 | $6,354,199,979 | +$99,938,486 | $31.02 | 310 |
| 2015 Q2 | 202,360,344 | $6,272,925,402 | +$139,531,654 | $31.00 | 336 |
| 2015 Q1 | 195,915,658 | $7,145,807,657 | +$5,902,683,517 | $36.48 | 327 |
| 2014 Q4 | 33,972,016 | $1,313,392,000 | +$1,189,574,261 | $38.66 | 25 |
| 2014 Q3 | 3,202,724 | $104,569,000 | $32.65 | 1 | |
| 2014 Q2 | 0 | $0 | -$3,340,000 | $103.30 | 0 |
| 2014 Q1 | 121,496 | $3,353,169 | +$561,542 | $32.03 | 2 |