Ranked by reported Q1 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. | 33.0M | $3.37B | +0.3% | 11.100% | 0.06% |
| 2 | VANGUARD PORTFOLIO MANAGEMENT LLC | 25.0M | $2.56B | — | 8.409% | 0.14% |
| 3 | VANGUARD CAPITAL MANAGEMENT LLC | 18.8M | $1.92B | — | 6.306% | 0.05% |
| 4 | STATE STREET CORP | 17.6M | $1.81B | +3.9% | 5.900% | 0.06% |
| 5 | GEODE CAPITAL MANAGEMENT, LLC | 8.5M | $863.7M | +2.3% | 2.853% | 0.05% |
| 6 | FMR LLC | 7.5M | $764.5M | -6.3% | 2.516% | 0.04% |
| 7 | MORGAN STANLEY | 4.7M | $475.2M | +29.3% | 1.564% | 0.03% |
| 8 | PRINCIPAL FINANCIAL GROUP INC | 4.6M | $466.4M | +8.5% | 1.535% | 0.25% |
| 9 | DIMENSIONAL FUND ADVISORS LP | 4.6M | $464.9M | +2.8% | 1.530% | 0.10% |
| 10 | NORTHERN TRUST CORP | 4.2M | $423.9M | -0.1% | 1.395% | 0.06% |
| 11 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 4.0M | $409.9M | +3.4% | 1.349% | 0.06% |
| 12 | Invesco Ltd. | 3.9M | $400.5M | -11.2% | 1.318% | 0.06% |
| 13 | Legal & General Group Plc | 3.1M | $320.2M | -6.6% | 1.054% | 0.07% |
| 14 | Daiwa Securities Group Inc. | 3.1M | $317.4M | -15.0% | 1.045% | 1.01% |
| 15 | DEUTSCHE BANK AG\ | 3.1M | $315.8M | +21.6% | 1.039% | 0.10% |
| 16 | PRUDENTIAL FINANCIAL INC | 2.4M | $246.8M | +4.6% | 0.812% | 0.30% |
| 17 | CENTERSQUARE INVESTMENT MANAGEMENT LLC | 2.3M | $235.9M | -12.2% | 0.776% | 2.44% |
| 18 | GOLDMAN SACHS GROUP INC | 2.2M | $226.4M | +45.4% | 0.745% | 0.03% |
| 19 | Vontobel Holding Ltd. | 2.1M | $216.2M | +25.3% | 0.712% | 0.74% |
| 20 | Nuveen, LLC | 2.1M | $211.3M | -2.8% | 0.695% | 0.06% |
| 21 | Capital World Investors | 1.9M | $190.7M | -11.8% | 0.628% | 0.03% |
| 22 | AMERIPRISE FINANCIAL INC | 1.9M | $189.1M | +6.1% | 0.622% | 0.04% |
| 23 | AQR CAPITAL MANAGEMENT LLC | 1.8M | $183.1M | +100.0% | 0.621% | 0.08% |
| 24 | VANGUARD FIDUCIARY TRUST CO | 1.7M | $168.8M | — | 0.556% | 0.04% |
| 25 | Bank of New York Mellon Corp | 1.6M | $166.0M | -3.6% | 0.546% | 0.03% |
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 Q1 2026, grouped by how each filer changed its position.
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 |
|---|---|---|---|---|---|---|
| Q1 2026 | 1,058 | +8.7% | 61.42% | +11.70 pp | $23.25B | +24% |
| Q4 2025 | 973 | +0.0% | 49.72% | 10.74 pp | $18.82B | 18% |
| Q3 2025 | 973 | 3.9% | 60.46% | 6.04 pp | $22.89B | 9.1% |
| Q2 2025 | 1,012 | +4.9% | 66.50% | +17.05 pp | $25.17B | +34% |
| Q1 2025 | 965 | 5.2% | 49.45% | 12.37 pp | $18.72B | 20% |
| Q4 2024 | 1,018 | +0.9% | 61.82% | 3.88 pp | $23.40B | 5.9% |
| Q3 2024 | 1,009 | +8.5% | 65.70% | +13.81 pp | $24.87B | +27% |
| Q2 2024 | 930 | — | 51.89% | — | $19.64B | — |
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 Q1 2026 13F filings, institutional ownership of Iron Mountain Incorporated stands at 61.4%, held across 1,058 reporting institutions.
BlackRock, Inc. is the largest reported institutional holder of IRM, with approximately 33,021,354 shares worth $3.37B as of Q1 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 55 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
191 institutions opened new positions in IRM during Q1 2026, while 106 fully exited. 758 added to existing positions and 103 trimmed.
IRM institutional ownership rose by 11.70 percentage points quarter-over-quarter, with a net change of +85 holders.
The top 10 institutions account for 56.4% of all reported 13F value in IRM, and the top 25 account for 72.7%.
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