Iron Mountain Inc (IRM) Institutional Ownership

Institutions by Trading Activity

Ownership Statistics

295,083,673Shares Outstanding

4,817,958Shares held by institutions

$524,145,651Value of institutional holdings

84.39%Institutional ownership %

4.09%Shares Changed QoQ

942No. of institutional investors

Shares Owned by Institutions

Shares Purchased/Sold by Institutions

Ownership Summary

Recent 13F filings as of December 2025 show that 942 institutional investors hold a position in Iron Mountain Inc (NYSE:IRM).

These investors collectively held 84.4% of the company's total shares outstanding in December 2025, down from 86.1% in September 2025.
The company experienced a 4.09% quarterly change in institutional shares held, alongside a decrease of 9.60% in total owners annually.
Of these 942 institutional investors, 406 increased their holdings in Iron Mountain, while 388 of them reduced positions, and 148 investors maintained their exposure.
Collectively, institutional investors increased their stake in Iron Mountain to 249.03Mn shares as of December 2025, a change that is up by 9.79Mn shares quarter on quarter and up 14.09Mn shares year over year.
VANGUARD GROUP INC continues to be the largest institutional holder of Iron Mountain as of December 31, 2025, with a position of 46.63Mn shares, representing 15.80% of the company's outstanding stock.
Among the most significant buyers of Iron Mountain during December 2025 were NORGES BANK (4.45Mn), COHEN & STEERS, INC. (3.16Mn), PRINCIPAL FINANCIAL GROUP INC (1.68Mn), BlackRock, Inc. (1.21Mn), CITADEL ADVISORS LLC (1.06Mn).
Leading sellers of Iron Mountain stock in December 2025 included UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC (3.16Mn), ROYAL BANK OF CANADA (1.01Mn), VANGUARD GROUP INC (625.62K), UBS Group AG (624.49K), CAPTRUST FINANCIAL ADVISORS (513.12K).
The top 10 institutional holders of Iron Mountain for the quarter ending December 2025 included VANGUARD GROUP INC (46.63Mn), BlackRock, Inc. (32.92Mn), COHEN & STEERS, INC. (18.90Mn), STATE STREET CORP (16.89Mn), GEODE CAPITAL MANAGEMENT, LLC (8.29Mn), FMR LLC (7.98Mn), NORGES BANK (4.45Mn), DIMENSIONAL FUND ADVISORS LP (4.43Mn), PRINCIPAL FINANCIAL GROUP INC (4.21Mn), NORTHERN TRUST CORP (4.15Mn).

942 Institutional Holders

4,817,958 Total Shares Held

Rows:

Download Data

Owner Name	Date	Shares Held	Change (QoQ)	Change (%)	Value (USD)
VANGUARD GROUP INC	31 Dec, 2025	46,627,483	-625,617	-1.32%	$3,867,749,715.00
BlackRock, Inc.	31 Dec, 2025	32,919,658	1,210,594	3.82%	$2,730,685,613.00
COHEN & STEERS, INC.	31 Dec, 2025	18,903,716	3,155,034	20.03%	$1,568,110.00
STATE STREET CORP	31 Dec, 2025	16,888,798	-242,989	-1.42%	$1,415,001,718.00
GEODE CAPITAL MANAGEMENT, LLC	31 Dec, 2025	8,292,653	102,073	1.25%	$685,374,233.00
FMR LLC	31 Dec, 2025	7,984,304	126,212	1.61%	$662,298,027.00
NORGES BANK	31 Dec, 2025	4,447,133	4,447,133	0.00%	$368,889,682.00
DIMENSIONAL FUND ADVISORS LP	31 Dec, 2025	4,429,359	81,320	1.87%	$367,418,097.00
PRINCIPAL FINANCIAL GROUP INC	31 Dec, 2025	4,207,596	1,680,438	66.50%	$349,020,857.00
NORTHERN TRUST CORP	31 Dec, 2025	4,152,569	121,003	3.00%	$344,455,599.00
CHARLES SCHWAB INVESTMENT MANAGEMENT INC	31 Dec, 2025	3,880,275	206,030	5.61%	$321,868,811.00
Daiwa Securities Group Inc.	31 Dec, 2025	3,654,086	502,998	15.96%	$303,106.00
MORGAN STANLEY	31 Dec, 2025	3,598,973	-12,426	-0.34%	$298,534,997.00
Legal & General Group Plc	31 Dec, 2025	3,356,420	140,965	4.38%	$278,415,040.00
Contour Asset Management LLC	31 Dec, 2025	2,832,182	-333,648	-10.54%	$234,929,497.00
CENTERSQUARE INVESTMENT MANAGEMENT LLC	31 Dec, 2025	2,631,453	116,989	4.65%	$218,279,027.00
DEUTSCHE BANK AG\	31 Dec, 2025	2,541,992	-348,459	-12.06%	$210,858,237.00
PRUDENTIAL FINANCIAL INC	31 Dec, 2025	2,310,481	196,864	9.31%	$191,654,398.00
Pictet Asset Management Holding SA	31 Dec, 2025	2,295,965	-168,203	-6.83%	$190,433,581.00
Nuveen, LLC	31 Dec, 2025	2,127,931	-14,574	-0.68%	$176,511,876.00

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