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Iron Mountain

1,043 hedge funds and large institutions have $25.5B invested in Iron Mountain in 2025 Q2 according to their latest regulatory filings, with 119 funds opening new positions, 393 increasing their positions, 357 reducing their positions, and 62 closing their positions.

New
Increased
Maintained
Reduced
Closed

92% more first-time investments, than exits

New positions opened: 119 | Existing positions closed: 62

60% more funds holding in top 10

Funds holding in top 10: 1016 (+6)

21% more capital invested

Capital invested by funds: $21.1B → $25.5B (+$4.43B)

10% more repeat investments, than reductions

Existing positions increased: 393 | Existing positions reduced: 357

5% more funds holding

Funds holding: 9941,043 (+49)

0.76% more ownership

Funds ownership: 83.58%84.34% (+0.76%)

43% less call options, than puts

Call options by funds: $102M | Put options by funds: $179M

Holders
1,043
Holders Change
+49
Holders Change %
+4.93%
% of All Funds
13.73%
Holding in Top 10
16
Holding in Top 10 Change
+6
Holding in Top 10 Change %
+60%
% of All Funds
0.21%
New
119
Increased
393
Reduced
357
Closed
62
Calls
$102M
Puts
$179M
Net Calls
-$77.2M
Net Calls Change
-$30.7M
Name Holding Trade Value Shares
Change
Change in
Stake
RhumbLine Advisers
51
RhumbLine Advisers
Massachusetts
$63.6M -$4.16M -44,107 -7%
ACM
52
AEW Capital Management
Massachusetts
$63.6M -$4.67M -49,590 -7%
D.E. Shaw & Co
53
D.E. Shaw & Co
New York
$59.9M -$22M -233,469 -29%
Millennium Management
54
Millennium Management
New York
$59.1M -$11.3M -119,925 -17%
AAMU
55
APG Asset Management US
New York
$58.2M
AllianceBernstein
56
AllianceBernstein
Tennessee
$57.6M -$3.62M -38,428 -6%
Adage Capital Partners
57
Adage Capital Partners
Massachusetts
$57.5M +$22.8M +242,200 +76%
Asset Management One
58
Asset Management One
Japan
$57M +$88.2K +936 +0.2%
Barclays
59
Barclays
United Kingdom
$55.8M -$9.46M -100,350 -16%
Nomura Asset Management
60
Nomura Asset Management
Japan
$53.1M +$1.85M +19,609 +4%
ZIG
61
Zurich Insurance Group
Switzerland
$52.7M +$48.4M +513,791 New
California Public Employees Retirement System
62
California Public Employees Retirement System
California
$50.7M +$1.38M +14,684 +3%
BTCPP
63
Border to Coast Pensions Partnership
United Kingdom
$49.2M
Universal-Beteiligungs- und Servicegesellschaft
64
Universal-Beteiligungs- und Servicegesellschaft
Germany
$49M +$10.4M +110,583 +30%
National Pension Service
65
National Pension Service
South Korea
$48.8M +$305K +3,240 +0.7%
HRES
66
Heitman Real Estate Securities
Illinois
$47.5M -$7.21M -76,519 -14%
SSA
67
Schonfeld Strategic Advisors
New York
$47.5M +$27.1M +287,249 +163%
UBS AM
68
UBS AM
Illinois
$46.5M +$2.89M +30,606 +7%
California State Teachers Retirement System (CalSTRS)
69
California State Teachers Retirement System (CalSTRS)
California
$46.4M +$2.01M +21,277 +5%
Canada Life
70
Canada Life
Manitoba, Canada
$44.9M -$548K -5,815 -1%
Rockefeller Capital Management
71
Rockefeller Capital Management
New York
$43.9M -$4.59M -48,676 -11%
BNP Paribas Financial Markets
72
BNP Paribas Financial Markets
France
$43.8M -$14.3M -151,549 -26%
ACM
73
Adelante Capital Management
California
$41.4M +$1.21M +12,859 +3%
Raymond James Financial
74
Raymond James Financial
Florida
$40.3M +$534K +5,662 +1%
Balyasny Asset Management
75
Balyasny Asset Management
Illinois
$39.8M -$15.6M -165,351 -30%

IRM Hedge Fund Activity: Q2 2025 in Review

1,043 of the 7,595 institutional investors tracked by Wall St. Rank reported a position in Iron Mountain (IRM) for Q2 2025, worth a combined $25.5B — up 21% from $21.1B a quarter earlier.

Buyers outnumbered sellers: 119 funds opened new IRM positions and 62 closed out — a net gain of 57 holders — while 393 added to existing stakes and 357 trimmed.

The largest buyer was Principal Financial Group, adding an estimated $158M. The largest seller was BlackRock, cutting an estimated $372M.

  • 1,043 institutional investors held Iron Mountain (IRM) as of Q2 2025, up from 994 in Q1 2025.
  • Funds reported $25.5B of Iron Mountain stock for Q2 2025, up 21% quarter-over-quarter.
  • 119 funds opened new Iron Mountain positions in Q2 2025 and 62 closed out, a net change of +57 holders.
  • The largest Iron Mountain buyer in Q2 2025 was Principal Financial Group, an estimated $158M added.
  • The largest Iron Mountain seller in Q2 2025 was BlackRock, an estimated $372M sold.

Based on aggregated 13F filings for Q2 2025.