Altimmune, Inc. (ALT) Ownership
ALT ownership summary
as of October 17, 2026- Institutions
- 78.0% of shares outstanding
- Insiders
- 0.43% of shares outstanding
- Shares outstanding
- 194.5M
- Float
- 164.3M shares available to trade
- Short interest
- 23.72% 46.1M shares short
- Days to cover
- 11.98 short interest down 11.0% vs prior month
- Institutions 78.00%
- Insiders 0.43%
- Other investors 21.57%
ALT top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | BlackRock Inc | 10.48% | 20.4M | $44.8M | +7.6M (+59.3%) | June 30, 2026 |
| 2 | Deep Track Capital, LP | 9.90% | 19.2M | $42.4M | +19.2M (0.0%) | June 30, 2026 |
| 3 | State Street Corp | 6.22% | 12.1M | $26.6M | +5.0M (+69.3%) | June 30, 2026 |
| 4 | TCG Crossover Management, LLC | 5.14% | 10.0M | $22.0M | +10.0M (0.0%) | June 30, 2026 |
| 5 | Vanguard Capital Management, LLC | 4.20% | 8.2M | $18.0M | +2.5M (+44.5%) | June 30, 2026 |
| 6 | Vanguard Portfolio Management, LLC | 3.77% | 7.3M | $16.1M | +1.9M (+36.2%) | June 30, 2026 |
| 7 | Marshall Wace Asset Management Ltd | 3.52% | 6.8M | $15.1M | +2.8M (+70.3%) | June 30, 2026 |
| 8 | Viking Global Investors LP | 3.44% | 6.7M | $14.7M | +6.7M (0.0%) | June 30, 2026 |
| 9 | RA Capital Management, LLC | 3.34% | 6.5M | $14.3M | +6.5M (0.0%) | June 30, 2026 |
| 10 | Geode Capital Management, LLC | 2.58% | 5.0M | $11.0M | +1.9M (+61.3%) | June 30, 2026 |
| 11 | Woodline Partners LP | 1.75% | 3.4M | $7.5M | +3.4M (0.0%) | June 30, 2026 |
| 12 | Millennium Management LLC | 1.70% | 3.3M | $7.3M | +50,931 (+1.6%) | June 30, 2026 |
| 13 | Nantahala Capital Management, LLC | 1.54% | 3.0M | $6.6M | +3.0M (0.0%) | June 30, 2026 |
| 14 | Trails Edge Capital Partners, LP | 1.37% | 2.7M | $5.9M | +2.7M (0.0%) | June 30, 2026 |
| 15 | Nuveen, LLC | 1.24% | 2.4M | $5.3M | +70,753 (+3.0%) | June 30, 2026 |
| 16 | Two Sigma Investments LLC | 1.22% | 2.4M | $5.2M | −97,758 (−3.9%) | June 30, 2026 |
| 17 | The Goldman Sachs Group Inc | 1.14% | 2.2M | $4.9M | +863,801 (+64.0%) | June 30, 2026 |
| 18 | Great Point Partners LLC | 0.90% | 1.7M | $3.8M | +1.7M (0.0%) | June 30, 2026 |
| 19 | Northern Trust Corp | 0.82% | 1.6M | $3.5M | +602,505 (+60.4%) | June 30, 2026 |
| 20 | Weiss Asset Management LP | 0.79% | 1.5M | $3.4M | +1.5M (0.0%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 19 holders added 78.1M shares and 1 cut 98K.
ALT top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.96% | 5.7M | $12.6M | — | August 31, 2026 |
| 2 | iShares Russell 2000 ETF | 2.56% | 5.0M | $10.9M | −57,344 (−1.1%) | September 30, 2026 |
| 3 | State Street® SPDR® S&P® Biotech ETF | 2.30% | 4.5M | $9.9M | −85,600 (−1.9%) | September 30, 2026 |
| 4 | Vanguard Strategic Equity Inv | 1.37% | 2.7M | $5.9M | +835,788 (+45.6%) | June 30, 2026 |
| 5 | Fidelity Small Cap Index | 1.12% | 2.2M | $4.8M | +11,290 (+0.5%) | July 31, 2026 |
| 6 | iShares Russell 2000 Value ETF | 0.92% | 1.8M | $3.9M | +2,718 (+0.2%) | September 30, 2026 |
| 7 | iShares Biotechnology ETF | 0.75% | 1.5M | $3.2M | −11,104 (−0.8%) | September 30, 2026 |
| 8 | Fidelity Enhanced Small Cap Core ETF | 0.75% | 1.4M | $3.2M | +3,039 (+0.2%) | September 30, 2026 |
| 9 | BlackRock Advantage Small Cap Core Instl | 0.70% | 1.4M | $3.0M | +9,822 (+0.7%) | August 31, 2026 |
| 10 | Vanguard Explorer Inv | 0.62% | 1.2M | $2.7M | — | June 30, 2026 |
| 11 | Vanguard Russell 2000 ETF | 0.59% | 1.1M | $2.5M | +25,855 (+2.3%) | August 31, 2026 |
| 12 | Vanguard Strategic Small-Cap Equity Inv | 0.45% | 867K | $1.9M | +238,994 (+38.0%) | June 30, 2026 |
| 13 | Fidelity Extended Market Index | 0.41% | 797K | $1.8M | −234,709 (−22.7%) | August 31, 2026 |
| 14 | iShares Micro-Cap ETF | 0.31% | 606K | $1.3M | −4,178 (−0.7%) | September 30, 2026 |
| 15 | Schwab Small Cap Index | 0.25% | 484K | $1.1M | — | August 31, 2026 |
| 16 | Vanguard Health Care ETF | 0.25% | 477K | $1.0M | −96,583 (−16.8%) | August 31, 2026 |
| 17 | Stt Strt SPDR® Russell2000 US SmCapETF | 0.21% | 409K | $898,977 | +19,552 (+5.0%) | August 31, 2026 |
| 18 | Vanguard Market Neutral I | 0.21% | 401K | $881,661 | +57,048 (+16.6%) | June 30, 2026 |
| 19 | BSF Systematic US Eq Abs Ret A2 USD | 0.19% | 377K | $829,684 | +53,431 (+16.5%) | December 31, 2025 |
| 20 | iShares Russell 2000 Small-Cap Idx Instl | 0.19% | 372K | $817,456 | — | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
ALT insider transactions
latest 6| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-06 | Gregory L Weaver | Buy | $3.54 | 5,000 | $17,700 |
| 2026-03-06 | Jerome Benedict Durso | Buy | $3.54 | 20,000 | $70,800 |
| 2026-01-08 | Wayne Pisano | Buy | $4.08 | 5,000 | $20,400 |
| 2025-12-29 | Diane Jorkasky | Buy | $3.80 | 527 | $2,003 |
| 2025-12-23 | John Gill | Buy | $4.10 | 12,500 | $51,250 |
| 2025-12-22 | Jerome Benedict Durso | Buy | $4.13 | 12,500 | $51,625 |
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.
ALT shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns ALT
Institutional investors own 78.0% of Altimmune's shares and insiders 0.43%. The largest holder is BlackRock Inc with 10.48% of the shares (20.4M), as of June 30, 2026. Among the top 20 institutions, 19 added shares and 1 reduced their stake in the latest filings. Short interest is 23.72% of the float, or 11.98 days of average trading volume. The share count rose 47,069.9% since 2014.
Related: ALT analyst forecast, ALT key metrics. See the ALT stock overview for the latest quote and news.
ALT ownership FAQ
Who owns the most Altimmune stock?
The largest shareholders of Altimmune are BlackRock Inc (10.48%), Deep Track Capital, LP (9.90%), State Street Corp (6.22%), TCG Crossover Management, LLC (5.14%), Vanguard Capital Management, LLC (4.20%).
What percentage of Altimmune is owned by institutions?
Institutions hold 78.0% of Altimmune's shares outstanding; insiders hold 0.43%.
Which funds own Altimmune?
The largest fund holders of Altimmune are Vanguard MStar Total Stk Mkt Idx Invest (2.96%), iShares Russell 2000 ETF (2.56%), State Street® SPDR® S&P® Biotech ETF (2.30%), Vanguard Strategic Equity Inv (1.37%), Fidelity Small Cap Index (1.12%).
What is Altimmune's short interest?
46.1M shares of Altimmune were sold short, 23.72% of the float; at the average daily volume it would take 11.98 days to cover.
Are insiders buying or selling Altimmune?
Of the latest 6 reported insider transactions in Altimmune (since December 22, 2025), 6 were purchases and 0 were sales.
How many shares of Altimmune are outstanding?
Altimmune has 194.5M shares outstanding, of which 164.3M are in the public float.