Iron Mountain Ownership | Who Owns Iron Mountain?

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Iron Mountain Ownership Summary

Iron Mountain is owned by 74.23% institutional investors, 0.78% insiders, and 24.99% retail investors. Vanguard group is the largest institutional shareholder, holding 16.00% of IRM shares. Vanguard Real Estate Index Investor is the top mutual fund, with 3.70% of its assets in Iron Mountain shares.

IRM Ownership Benchmark

Type	Name	% Inst	% Insiders	% Retail
Stock	Iron Mountain	74.23%	0.78%	24.99%
Sector	Real Estate Stocks	49.33%	9.10%	41.57%
Industry	Specialty REIT Stocks	67.27%	3.51%	29.22%

Institutional Shareholders

Top Institutional Shareholders by Total Shares

Holder	Shares	% Holding	Value
Vanguard group	47.25M	16.00%	$4.82B
Blackrock funding, inc. /de	31.71M	10.74%	$3.23B
Blackrock	27.89M	9.53%	$2.50B
State street	17.13M	5.80%	$1.76B
Cohen & steers	15.75M	5.33%	$1.61B
Geode capital management	8.19M	2.77%	$831.73M
Fmr	7.86M	2.66%	$801.05M
Invesco	5.07M	1.72%	$516.48M
Dimensional fund advisors lp	4.35M	1.47%	$443.22M
Northern trust	4.03M	1.36%	$410.98M

Top Institutional Shareholders by % of Total Assets

Holder	Shares	% Assets	Value
Contour asset management	3.17M	8.09%	$322.72M
Waterfront capital partners	115.29K	7.69%	$11.75M
Foresight capital management advisors	82.05K	4.70%	$8.36M
Vert asset management	134.58K	4.61%	$13.72M
B&i capital	102.97K	3.63%	$10.50M
Marble harbor investment counsel	325.26K	3.47%	$33.16M
Heitman real estate securities	474.37K	3.30%	$48.36M
Cohen & steers	15.75M	2.90%	$1.61B
Ar asset management	130.60K	2.81%	$13.31M
Pggm investments	1.68M	2.78%	$171.75M

Top Buyers

Holder	Shares	% Assets	Change
Blackrock	27.89M	0.06%	4.78M
Norges bank	3.31M	0.05%	3.31M
Ubs asset management americas	3.16M	0.07%	2.71M
Cohen & steers	15.75M	2.90%	1.98M
Fmr	7.86M	0.04%	1.16M

Top Sellers

Holder	Shares	% Assets	Change
Citadel advisors	-	-	-1.27M
Wellington management group llp	248.89K	0.00%	-1.25M
Deutsche bank ag\	2.89M	0.10%	-539.03K
Goldman sachs group	1.35M	0.02%	-525.87K
Amundi	1.09M	0.04%	-515.51K

New Positions

Holder	Shares	% Assets	Change	Value
Norges bank	3.31M	0.05%	3.31M	$348.25M
Axa investment managers	113.35K	0.03%	113.35K	$11.55M
Summit partners public asset management	85.00K	0.18%	85.00K	$8.66M
Tcw group	81.02K	0.07%	81.02K	$8.26M
Fjarde ap-fonden (the fourth swedish national pensionfund)	38.18K	0.04%	38.18K	$3.42M

Sold Out

Holder	Change
Mendota financial group	-1.00
Financial gravity asset management	-1.00
Cape investment advisory	-1.00
Westend advisors	-2.00
Reston wealth management	-3.00

Institutional Ownership Trends

Date	Holdings	Change %	Shares	Change %	Ownership	Change %	Increased Position	Change %	Decreased Position	Change %
Sep 30, 2025	898	-14.96%	219,243,090	-9.07%	74	1.11%	385	-24.21%	329	-6.00%
Jun 30, 2025	1,058	4.65%	248,166,621	3.56%	84	1.27%	506	18.50%	353	-11.75%
Mar 31, 2025	996	-8.03%	240,406,567	1.52%	81	1.25%	417	-13.13%	397	-3.64%
Dec 31, 2024	781	-27.82%	190,161,466	-20.39%	64	0.98%	327	-31.30%	315	-24.82%
Sep 30, 2024	1,072	8.83%	238,410,694	-3.76%	81	1.14%	475	9.20%	411	11.08%

Top Mutual Funds Shareholders

Holder	Shares	% Holding	Change
Vanguard Real Estate Index Investor	10.91M	3.70%	12.83K
Vanguard US Total Market Shares ETF	9.29M	3.16%	12.82K
Vanguard Total Stock Mkt Idx Inv	9.27M	3.14%	-219.41K
Vanguard Institutional 500 Index Trust	8.35M	2.83%	58.03K
Vanguard 500 Index Investor	7.30M	2.47%	-1.07M
Vanguard Mid Cap Index Institutional	6.58M	2.23%	70.93K
Fidelity 500 Index	3.74M	1.27%	1.60K
SPDR® S&P 500 ETF	3.56M	1.21%	-144.37K
SPDR® S&P 500® ETF Trust	3.56M	1.21%	-18.68K
SPDR® S&P 500® ETF	3.57M	1.21%	43.77K

Recent Insider Transactions

Date	Name	Role	Activity	Value
Dec 01, 2025	Kidd Mark	EVP, GM Data Centers & ALM	Sell	$510.00K
Dec 01, 2025	Meaney William L	President and CEO	Sell	$887.10K
Dec 01, 2025	Meaney William L	President and CEO	Sell	$4.87M
Nov 19, 2025	Kelly Christie B.	-	Buy	$2.95K
Nov 03, 2025	Meaney William L	President and CEO	Sell	$3.67M

Insider Transactions Trends

Date	Buy	Sell
2025 Q4	1	11
2025 Q3	-	13
2025 Q2	-	13
2025 Q1	-	21
2024 Q4	-	7

IRM Ownership FAQ

Who Owns Iron Mountain?

Iron Mountain shareholders are primarily institutional investors at 74.23%, followed by 0.78% insiders and 24.99% retail investors. The average institutional ownership in Iron Mountain's industry, Specialty REIT Stocks , is 67.27%, which Iron Mountain exceeds.

Who owns the most shares of Iron Mountain?

Iron Mountain’s largest shareholders are Vanguard group (47.25M shares, 16.00%), Blackrock funding, inc. /de (31.71M shares, 10.74%), and Blackrock (27.89M shares, 9.53%). Together, they hold 36.26% of Iron Mountain’s total shares outstanding.

Does Blackrock own Iron Mountain?

Yes, BlackRock owns 9.53% of Iron Mountain, totaling 27.89M shares as of Jun 2024. This represents 0.06% of BlackRock's total assets, with a market value of 2.5B$. In the last quarter, BlackRock increased its holdings by 4.78M shares, a 20.70% change.

Who is Iron Mountain’s biggest shareholder by percentage of total assets invested?

Contour asset management is Iron Mountain’s biggest shareholder by percentage of total assets invested, with 8.09% of its assets in 3.17M Iron Mountain shares, valued at 322.72M$.

Who is the top mutual fund holder of Iron Mountain shares?

Vanguard Real Estate Index Investor is the top mutual fund holder of Iron Mountain shares, with 3.70% of its total shares outstanding invested in 10.91M Iron Mountain shares.

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