IRON MOUNTAIN INC - Common Stock (IRM) Institutional Ownership

13F Institutional Holders and Ownership History from Q1 2014 to Q4 2025

Type / Class
Equity / Common Stock
Symbol
IRM on NYSE
Shares outstanding
295,766,873
Price per share
$91.54
All holders as of 31 Dec 2025
Q4 2025
Total 13F shares
255,954,029
Total reported value
$21,239,844,675
% of total 13F portfolios
0.01%
Share change
+6,454,438
Value change
+$498,471,414
Number of holders
985
Price from insider filings
$91.54
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors

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
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, 985 institutional investors reported holding 255,954,029 shares of IRON MOUNTAIN INC - Common Stock (IRM). This represents 87% of the company’s total 295,766,873 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 0.96% 2,832,182 -11% 5.5% $234,929,497
CENTERSQUARE INVESTMENT MANAGEMENT LLC 0.89% 2,631,453 +4.7% 2.2% $218,279,027
DEUTSCHE BANK AG\ 0.86% 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 0.78% 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 0.72% 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
2025 Q4 255,954,029 $21,239,844,675 +$498,471,414 $82.95 985
2025 Q3 250,044,036 $25,496,110,316 +$119,659,062 $101.94 1,006
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 $91.54 0
2014 Q1 121,496 $3,353,169 +$561,542 $32.03 2