Latest Period
Q1 2026
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
1,075
Shares (Excl. Options)
252,638,340
Price
$102.14
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- Type / Class
- Equity / Common Stock
- Symbol
- IRM on NYSE
- Shares outstanding
- 297,661,125
- Price per share
- $112.62
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 252,638,340
- Total reported value
- $25,788,989,800
- % of total 13F portfolios
- 0.02%
- Share change
- -3,970,256
- Value change
- -$298,354,220
- Number of holders
- 1,075
- Price from insider filings
- $112.62
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors
Key facts
- IRM - IRON MOUNTAIN INC - Common Stock is tracked under CUSIP 46284V101.
- 1075 institutions reported positions in Q1 2026.
- 3 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 1,002 to 1,075 between Q4 2025 and Q1 2026.
- Reported value moved from $21,344,426,677 to $25,788,989,800.
Research use
- 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.
Evidence
Source: SEC Form 13F
Open SEC Evidence
Latest holder context comes from 1075 institutions filings for Q1 2026.
Security key
46284V101
Latest holder period
Q1 2026
13F holders
1,075
13D/G owners
3
CIK / CUSIP context first
Open Q1 2026 holders
IRM full holder history
IRON MOUNTAIN INC SEC filings
IRON MOUNTAIN INC company facts
IRON MOUNTAIN INC insider transactions
Broader feeds
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. | 4.9% | -26% | $1,503,596,476 | -$470,109,106 | 14,555,629 | -24% | Cohen & Steers, Inc. | 30 Apr 2026 |
As of 31 Mar 2026, 1,075 institutional investors reported holding 252,638,340 shares of IRON MOUNTAIN INC - Common Stock (IRM). This represents 85% of the company’s total 297,661,125 outstanding shares.
Top 25 Institutional Shareholders
The largest institutional shareholders of IRON MOUNTAIN INC - Common Stock (IRM) together control 61% 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 |
|---|---|---|---|---|---|
| BlackRock, Inc. | 11% | 33,021,354 | +0.31% | 0.06% | $3,372,801,141 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 8.4% | 25,015,557 | 0% | 0.13% | $2,555,088,992 |
| VANGUARD CAPITAL MANAGEMENT LLC | 6.3% | 18,758,889 | 0% | 0.05% | $1,916,032,922 |
| STATE STREET CORP | 5.9% | 17,551,633 | +3.9% | 0.06% | $1,807,660,367 |
| COHEN & STEERS, INC. | 5.4% | 16,169,341 | -14% | 2.9% | $1,651,537,000 |
| GEODE CAPITAL MANAGEMENT, LLC | 2.9% | 8,486,127 | +2.3% | 0.05% | $863,699,269 |
| FMR LLC | 2.5% | 7,484,398 | -6.3% | 0.04% | $764,456,401 |
| MORGAN STANLEY | 1.6% | 4,652,247 | +29% | 0.03% | $475,180,655 |
| PRINCIPAL FINANCIAL GROUP INC | 1.5% | 4,566,093 | +8.5% | 0.25% | $466,382,473 |
| DIMENSIONAL FUND ADVISORS LP | 1.5% | 4,552,286 | +2.8% | 0.1% | $464,930,903 |
| NORTHERN TRUST CORP | 1.4% | 4,150,486 | -0.05% | 0.06% | $423,930,638 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 1.3% | 4,013,007 | +3.4% | 0.06% | $409,888,535 |
| Invesco Ltd. | 1.3% | 3,921,521 | -11% | 0.06% | $400,544,198 |
| Legal & General Group Plc | 1.1% | 3,135,074 | -6.6% | 0.07% | $320,216,461 |
| Daiwa Securities Group Inc. | 1% | 3,107,440 | -15% | 0.92% | $317,393,921 |
| DEUTSCHE BANK AG\ | 1% | 3,092,084 | +22% | 0.1% | $315,825,461 |
| PRUDENTIAL FINANCIAL INC | 0.81% | 2,416,063 | +4.6% | 0.3% | $246,776,675 |
| CENTERSQUARE INVESTMENT MANAGEMENT LLC | 0.78% | 2,310,045 | -12% | 2.4% | $235,947,996 |
| GOLDMAN SACHS GROUP INC | 0.74% | 2,216,672 | +45% | 0.03% | $226,410,923 |
| JPMORGAN CHASE & CO | 0.71% | 2,123,358 | +10% | 0.01% | $207,239,854 |
| Vontobel Holding Ltd. | 0.71% | 2,116,877 | +25% | 0.74% | $216,217,815 |
| Nuveen, LLC | 0.69% | 2,068,408 | -2.8% | 0.06% | $211,267,193 |
| Capital World Investors | 0.63% | 1,867,169 | -12% | 0.03% | $190,712,642 |
| AMERIPRISE FINANCIAL INC | 0.62% | 1,851,007 | +6.1% | 0.04% | $189,082,930 |
| AQR CAPITAL MANAGEMENT LLC | 0.62% | 1,846,073 | +100% | 0.08% | $183,074,982 |
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 | 252,638,340 | $25,788,989,800 | -$298,354,220 | $102.14 | 1,075 |
| 2025 Q4 | 257,161,631 | $21,344,426,677 | +$503,419,225 | $82.95 | 1,002 |
| 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 | $112.62 | 0 |
| 2014 Q1 | 121,496 | $3,353,169 | +$561,542 | $32.03 | 2 |