Iron Mountain Incorporated (IRM) Ownership
IRM ownership summary
as of October 18, 2026- Institutions
- 87.9% of shares outstanding
- Insiders
- 0.88% of shares outstanding
- Shares outstanding
- 297.7M
- Float
- 294.9M shares available to trade
- Short interest
- 3.19% 7.0M shares short
- Days to cover
- 4.09 short interest up 8.3% vs prior month
- Institutions 87.86%
- Insiders 0.88%
- Other investors 11.26%
IRM top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | BlackRock Inc | 11.28% | 33.6M | $3.78B | +549,556 (+1.7%) | June 30, 2026 |
| 2 | Vanguard Portfolio Management, LLC | 8.59% | 25.6M | $2.88B | +553,387 (+2.2%) | June 30, 2026 |
| 3 | Vanguard Capital Management, LLC | 6.37% | 19.0M | $2.13B | +194,816 (+1.0%) | June 30, 2026 |
| 4 | State Street Corp | 5.92% | 17.6M | $1.98B | +82,411 (+0.5%) | June 30, 2026 |
| 5 | Cohen & Steers Inc | 4.04% | 12.0M | $1.35B | −4.1M (−25.7%) | June 30, 2026 |
| 6 | Geode Capital Management, LLC | 2.91% | 8.6M | $973.1M | +163,122 (+1.9%) | June 30, 2026 |
| 7 | FMR Inc | 2.64% | 7.9M | $885.7M | +387,967 (+5.2%) | June 30, 2026 |
| 8 | Dimensional Fund Advisors, Inc. | 1.55% | 4.6M | $520.4M | +73,398 (+1.6%) | June 30, 2026 |
| 9 | Morgan Stanley - Brokerage Accounts | 1.49% | 4.4M | $498.1M | −225,325 (−4.8%) | June 30, 2026 |
| 10 | Principal Financial Group Inc | 1.47% | 4.4M | $492.1M | −192,669 (−4.2%) | June 30, 2026 |
| 11 | Charles Schwab Investment Management Inc | 1.43% | 4.3M | $479.7M | +250,480 (+6.2%) | June 30, 2026 |
| 12 | Northern Trust Corp | 1.42% | 4.2M | $475.1M | +72,481 (+1.7%) | June 30, 2026 |
| 13 | NORGES BANK | 1.42% | 4.2M | $474.2M | −232,436 (−5.2%) | June 30, 2026 |
| 14 | Amvescap Plc. | 1.37% | 4.1M | $457.4M | +144,128 (+3.7%) | June 30, 2026 |
| 15 | Legal & General Group PLC | 1.09% | 3.2M | $365.1M | +109,667 (+3.5%) | June 30, 2026 |
| 16 | UBS Asset Mgmt Americas Inc | 1.07% | 3.2M | $359.3M | +3.2M (+29,674.0%) | June 30, 2026 |
| 17 | Deutsche Bank AG | 1.02% | 3.0M | $343.1M | −43,005 (−1.4%) | June 30, 2026 |
| 18 | The Goldman Sachs Group Inc | 0.95% | 2.8M | $317.6M | +606,060 (+27.3%) | June 30, 2026 |
| 19 | CenterSquare Investment Management LLC | 0.78% | 2.3M | $261.5M | +13,929 (+0.6%) | June 30, 2026 |
| 20 | Nuveen, LLC | 0.75% | 2.2M | $249.6M | +150,363 (+7.3%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 15 holders added 6.5M shares and 5 cut 4.8M.
IRM top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard Real Estate Index Investor | 3.78% | 11.3M | $1.27B | +80,351 (+0.7%) | September 30, 2026 |
| 2 | Vanguard MStar Total Stk Mkt Idx Invest | 3.02% | 9.0M | $1.01B | −18,964 (−0.2%) | August 31, 2026 |
| 3 | Vanguard 500 Index Investor | 2.63% | 7.8M | $879.8M | −86,188 (−1.1%) | September 30, 2026 |
| 4 | Vanguard MStar Mid Cap Index Instl | 2.03% | 6.1M | $681.4M | −57,795 (−0.9%) | September 30, 2026 |
| 5 | iShares Core S&P 500 ETF | 1.33% | 4.0M | $446.3M | −6,401 (−0.2%) | September 30, 2026 |
| 6 | Fidelity 500 Index | 1.30% | 3.9M | $434.5M | +14,835 (+0.4%) | August 31, 2026 |
| 7 | State Street® SPDR® S&P 500® ETF | 1.23% | 3.7M | $411.9M | — | September 30, 2026 |
| 8 | Vanguard MStar Value Index Investor | 0.91% | 2.7M | $303.1M | −6,666 (−0.2%) | September 30, 2026 |
| 9 | State Street Real Estate Sel SectSPDRETF | 0.90% | 2.7M | $301.8M | +15,266 (+0.6%) | September 30, 2026 |
| 10 | Schwab US REIT ETF™ | 0.79% | 2.3M | $263.3M | +1,220 (+0.1%) | September 30, 2026 |
| 11 | Vanguard MStar Mid Cap Growth ETF | 0.75% | 2.2M | $249.8M | +48,963 (+2.3%) | September 30, 2026 |
| 12 | Cohen & Steers Instl Realty Shares | 0.74% | 2.2M | $248.3M | −2,527 (−0.1%) | September 30, 2026 |
| 13 | Vanguard Real Estate II Index | 0.67% | 2.0M | $224.4M | +14,357 (+0.7%) | September 30, 2026 |
| 14 | Cohen & Steers Realty Shares L | 0.64% | 1.9M | $214.6M | −106,808 (−5.3%) | September 30, 2026 |
| 15 | Cohen & Steers Real Estate Securities A | 0.64% | 1.9M | $214.0M | −67,901 (−3.4%) | September 30, 2026 |
| 16 | Invesco S&P 500® Equal Weight ETF | 0.57% | 1.7M | $191.0M | −3,515 (−0.2%) | September 30, 2026 |
| 17 | Vanguard Institutional Index I | 0.53% | 1.6M | $177.0M | −17,151 (−1.1%) | September 30, 2026 |
| 18 | DFA Real Estate Securities I | 0.52% | 1.6M | $175.0M | −59,217 (−3.7%) | August 31, 2026 |
| 19 | iShares Russell Mid-Cap ETF | 0.41% | 1.2M | $137.2M | +2,242 (+0.2%) | September 30, 2026 |
| 20 | iShares Core US REIT ETF | 0.38% | 1.1M | $127.9M | −8,998 (−0.8%) | September 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
IRM insider transactions
latest 20| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-04-01 | William L Meaney | Sell | $102.71 | 38,474 | $4.0M |
| 2026-04-01 | Mark Kidd | Sell | $102.71 | 6,000 | $616,260 |
| 2026-03-19 | Mithu Bhargava | Sell | $104.62 | 59,725 | $6.2M |
| 2026-03-05 | William L Meaney | Sell | $106.25 | 98,657 | $10.5M |
| 2026-03-04 | William L Meaney | Sell | $107.36 | 98,659 | $10.6M |
| 2026-03-02 | Jennifer Allerton | Sell | $108.88 | 7,000 | $762,160 |
| 2026-03-02 | Mark Kidd | Sell | $107.27 | 6,000 | $643,620 |
| 2026-03-02 | William L Meaney | Sell | $109.39 | 137,133 | $15.0M |
| 2026-02-04 | Markwayne Mullin | Sell | $90.00 | — | — |
| 2026-01-29 | Ro Khanna | Sell | $92.94 | — | — |
| 2026-01-23 | Ro Khanna | Buy | $93.59 | — | — |
| 2026-01-02 | Mark Kidd | Sell | $83.10 | 6,000 | $498,600 |
| 2026-01-02 | William L Meaney | Sell | $83.17 | 38,482 | $3.2M |
| 2025-12-18 | Markwayne Mullin | Sell | $78.95 | — | — |
| 2025-12-18 | Markwayne Mullin | Sell | $78.95 | — | — |
| 2025-12-01 | Mark Kidd | Sell | $85.00 | 6,000 | $510,000 |
| 2025-12-01 | William L Meaney | Sell | $83.34 | 69,125 | $5.8M |
| 2025-11-03 | Mark Kidd | Sell | $102.51 | 6,000 | $615,060 |
| 2025-11-03 | William L Meaney | Sell | $102.75 | 69,125 | $7.1M |
| 2025-10-31 | Mark Kidd | Sell | $100.82 | 7,306 | $736,591 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
IRM shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns IRM
Institutional investors own 87.9% of Iron Mountain's shares and insiders 0.88%. The largest holder is BlackRock Inc with 11.28% of the shares (33.6M), as of June 30, 2026. Among the top 20 institutions, 15 added shares and 5 reduced their stake in the latest filings. Short interest is 3.19% of the float, or 4.09 days of average trading volume. The share count rose 41.9% since 2014.
Related: IRM analyst forecast, IRM key metrics, IRM dividend history. See the IRM stock overview for the latest quote and news.
IRM ownership FAQ
Who owns the most Iron Mountain stock?
The largest shareholders of Iron Mountain are BlackRock Inc (11.28%), Vanguard Portfolio Management, LLC (8.59%), Vanguard Capital Management, LLC (6.37%), State Street Corp (5.92%), Cohen & Steers Inc (4.04%).
What percentage of Iron Mountain is owned by institutions?
Institutions hold 87.9% of Iron Mountain's shares outstanding; insiders hold 0.88%.
Which funds own Iron Mountain?
The largest fund holders of Iron Mountain are Vanguard Real Estate Index Investor (3.78%), Vanguard MStar Total Stk Mkt Idx Invest (3.02%), Vanguard 500 Index Investor (2.63%), Vanguard MStar Mid Cap Index Instl (2.03%), iShares Core S&P 500 ETF (1.33%).
What is Iron Mountain's short interest?
7.0M shares of Iron Mountain were sold short, 3.19% of the float; at the average daily volume it would take 4.09 days to cover.
Are insiders buying or selling Iron Mountain?
Of the latest 20 reported insider transactions in Iron Mountain (since October 31, 2025), 1 were purchases and 19 were sales.
How many shares of Iron Mountain are outstanding?
Iron Mountain has 297.7M shares outstanding, of which 294.9M are in the public float.