Ranked by reported Q2 2026 13F market value
Share of total reported institutional value in IRM held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 33.6M | $4.24B | +1.7% | 11.283% | 0.06% |
| 2 | VANGUARD PORTFOLIO MANAGEMENT LLC | 25.6M | $3.23B | +2.2% | 8.594% | 0.15% |
| 3 | VANGUARD CAPITAL MANAGEMENT LLC | 19.0M | $2.39B | +1.0% | 6.370% | 0.05% |
| 4 | STATE STREET CORP | 17.6M | $2.24B | +0.5% | 5.927% | 0.03% |
| 5 | GEODE CAPITAL MANAGEMENT, LLC | 8.6M | $1.09B | +1.9% | 2.907% | 0.06% |
| 6 | FMR LLC | 7.9M | $994.4M | +5.2% | 2.646% | 0.04% |
| 7 | DIMENSIONAL FUND ADVISORS LP | 4.6M | $584.3M | +1.6% | 1.555% | 0.11% |
| 8 | MORGAN STANLEY | 4.4M | $559.2M | -4.8% | 1.488% | 0.03% |
| 9 | PRINCIPAL FINANCIAL GROUP INC | 4.4M | $552.4M | -4.2% | 1.470% | 0.27% |
| 10 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 4.3M | $538.5M | +6.2% | 1.433% | 0.07% |
| 11 | NORTHERN TRUST CORP | 4.2M | $533.4M | +1.8% | 1.419% | 0.06% |
| 12 | NORGES BANK | 4.2M | $532.4M | — | 1.417% | 0.05% |
| 13 | Invesco Ltd. | 4.1M | $513.5M | +3.7% | 1.367% | 0.04% |
| 14 | Legal & General Group Plc | 3.2M | $409.8M | +3.5% | 1.091% | 0.09% |
| 15 | UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AME | 3.2M | $403.4M | +29674.0% | 1.073% | 0.07% |
| 16 | DEUTSCHE BANK AG\ | 3.0M | $385.1M | -1.4% | 1.025% | 0.11% |
| 17 | GOLDMAN SACHS GROUP INC | 2.8M | $356.5M | +27.3% | 0.949% | 0.03% |
| 18 | CENTERSQUARE INVESTMENT MANAGEMENT LLC | 2.3M | $293.5M | +0.6% | 0.781% | 2.51% |
| 19 | JPMORGAN CHASE & CO | 2.2M | $287.5M | +4.2% | 0.743% | 0.02% |
| 20 | Nuveen, LLC | 2.2M | $280.3M | +7.3% | 0.746% | 0.07% |
| 21 | AQR CAPITAL MANAGEMENT LLC | 2.1M | $266.5M | +15.2% | 0.715% | 0.09% |
| 22 | PRUDENTIAL FINANCIAL INC | 2.0M | $249.3M | -18.3% | 0.663% | 0.27% |
| 23 | Vontobel Holding Ltd. | 1.9M | $242.5M | -9.3% | 0.645% | 0.77% |
| 24 | Daiwa Securities Group Inc. | 1.9M | $235.1M | -40.1% | 0.626% | 0.46% |
| 25 | Select Equity Group, L.P. | 1.7M | $219.4M | -2.4% | 0.584% | 1.09% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in IRM — a direct measure of their conviction.
Filings activity in IRM during Q2 2026, grouped by how each filer changed its position.
Institutions that opened a new IRM position in Q2 2026
Institutions that fully closed their IRM position in Q2 2026
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q2 2026 | 1,164 | +8.0% | 87.45% | +0.74 pp | $30.54B | +28% |
| Q1 2026 | 1,078 | +9.7% | 86.71% | 1.02 pp | $23.83B | +26% |
| Q4 2025 | 983 | 0.4% | 87.73% | +1.98 pp | $18.94B | 18% |
| Q3 2025 | 987 | 2.5% | 85.75% | +0.95 pp | $23.02B | 8.6% |
| Q2 2025 | 1,012 | +4.9% | 84.80% | +2.17 pp | $25.17B | +34% |
| Q1 2025 | 965 | 5.2% | 82.63% | 1.03 pp | $18.72B | 20% |
| Q4 2024 | 1,018 | +0.9% | 83.66% | +1.18 pp | $23.40B | 5.9% |
| Q3 2024 | 1,009 | — | 82.48% | — | $24.87B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying IRM stock.
Based on Q2 2026 13F filings, institutional ownership of Iron Mountain Incorporated stands at 87.5%, held across 1,164 reporting institutions.
BlackRock, Inc. is the largest reported institutional holder of IRM, with approximately 33,570,910 shares worth $4.24B as of Q2 2026.
No marquee "smart money" managers (Berkshire, Burry, ARK, Tiger Global, Pershing Square, Baupost, etc.) currently appear among the top 25 institutional holders of IRM.
Our composite Smart Money Score for IRM is 53 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
132 institutions opened new positions in IRM during Q2 2026, while 60 fully exited. 885 added to existing positions and 106 trimmed.
IRM institutional ownership rose by 0.74 percentage points quarter-over-quarter, with a net change of +86 holders.
The top 10 institutions account for 53.8% of all reported 13F value in IRM, and the top 25 account for 70.8%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Iron Mountain Incorporated (IRM) Institutional Ownership