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
295,211,087
Price per share
$82.95
All holders as of 30 Sep 2025
Q3 2025
Total 13F shares
250,034,720
Total reported value
$25,495,173,447
% of total 13F portfolios
0.02%
Share change
+1,211,286
Value change
+$116,964,064
Number of holders
1,000
Price from insider filings
$82.95
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. 5.4% +27% $1,634,094,326 +$330,406,807 16,029,962 +25% Cohen & Steers, Inc. 30 Sep 2025

As of 30 Sep 2025, 1,000 institutional investors reported holding 250,034,720 shares of IRON MOUNTAIN INC - Common Stock (IRM). This represents 85% of the company’s total 295,211,087 outstanding shares.

Top 25 Institutional Shareholders

The largest institutional shareholders of IRON MOUNTAIN INC - Common Stock (IRM) together control 62% 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% 47,253,100 +0.4% 0.07% $4,816,981,013
BlackRock, Inc. 11% 31,709,064 +1.4% 0.06% $3,232,421,986
STATE STREET CORP 5.8% 17,131,787 +1.9% 0.06% $1,759,494,141
COHEN & STEERS, INC. 5.3% 15,748,682 +14% 2.9% $1,605,263,000
GEODE CAPITAL MANAGEMENT, LLC 2.8% 8,190,580 +1.3% 0.05% $831,727,030
FMR LLC 2.7% 7,858,092 +17% 0.04% $801,053,914
Invesco Ltd. 1.7% 5,066,516 +18% 0.08% $516,480,643
DIMENSIONAL FUND ADVISORS LP 1.5% 4,348,039 +1.3% 0.1% $443,221,764
NORTHERN TRUST CORP 1.4% 4,031,566 -0.89% 0.05% $410,977,838
CHARLES SCHWAB INVESTMENT MANAGEMENT INC 1.2% 3,674,245 +1.3% 0.06% $374,552,535
MORGAN STANLEY 1.2% 3,611,399 +3% 0.02% $368,146,293
Legal & General Group Plc 1.1% 3,215,455 -2.1% 0.07% $327,783,482
Contour Asset Management LLC 1.1% 3,165,830 +36% 8.1% $322,724,710
UBS AM, A DISTINCT BUSINESS UNIT OF UBS ASSET MANAGEMENT AMERICAS LLC 1.1% 3,161,589 +598% 0.07% $322,292,383
Daiwa Securities Group Inc. 1.1% 3,151,088 +6.6% 1.1% $321,221,000
DEUTSCHE BANK AG\ 0.98% 2,890,451 -16% 0.1% $294,652,575
PRINCIPAL FINANCIAL GROUP INC 0.86% 2,527,158 -2.2% 0.13% $257,619,252
CENTERSQUARE INVESTMENT MANAGEMENT LLC 0.85% 2,514,464 +24% 2.6% $256,324,461
Pictet Asset Management Holding SA 0.83% 2,464,168 -0.46% 0.24% $251,114,890
ROYAL BANK OF CANADA 0.78% 2,298,983 +13% 0.04% $234,357,000
Nuveen, LLC 0.73% 2,142,505 +4.3% 0.06% $218,406,960
Capital World Investors 0.72% 2,117,169 0% 0.03% $215,824,208
PRUDENTIAL FINANCIAL INC 0.72% 2,113,617 +8.6% 0.26% $215,462,117
JPMORGAN CHASE & CO 0.7% 2,056,448 +4.2% 0.01% $209,634,432
Russell Investments Group, Ltd. 0.58% 1,706,435 -6.4% 0.2% $173,906,132

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 2,330,043 $193,581,855 +$6,764,380 $82.95 121
2025 Q3 250,034,720 $25,495,173,447 +$116,964,064 $101.94 1,000
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 $82.95 0
2014 Q1 121,496 $3,353,169 +$561,542 $32.03 2