Altimmune ALT
$2.08 +$0.11 (+5.58%)
Market closed · Nov 6, 8:10 pm ET · Last extended-hours $2.07 -0.48%
Open$1.97
Prev close$1.97
Day range$1.95 – $2.10
Volume2.77M
Market cap$404.60M
P/E (TTM)–
Dividend yield–
Ownership & positioning
Who holds it, who is betting against it, and where the big money is moving
Institutional ownership77.7%-1.21 pts vs. prior quarter
Institutions holding237-5 vs. prior quarter
Insider trades (recent)38 buys / 12 sellsNet buying
Short interest21.71% of floatDays to cover 10.4 · as of 15 Oct 2026
Short-sale volume share24.4%5-day average of daily volume
Short-sale volume as % of daily volume
Large-order net flow, last 20 sessions
Net of large-order buying minus selling, in USD. Over this window: −$3.94M (7 inflow days, 13 outflow days).
Net flow by order size, last 20 sessions
Super/Big orders approximate institutional-size trades; Mid/Small approximate retail-size trades. Net buy minus sell value in each bucket, summed over the window.
The five largest holders on file together own 36.6% of shares outstanding.
Largest holders
By investor type
Reported short interest has fallen from 26.71% to 21.71% of float over the last 6 biweekly reports (31 Jul 2026 to 15 Oct 2026).
Recent institutional activity
| Holder | Type | Period | Share change | New stake |
|---|---|---|---|---|
| Deep Track Capital, LP | VC/PE Fund | 2026/Q3 | +19,250,000 | 9.9% |
| TCG Crossover Management, LLC | VC/PE Fund | 2026/Q3 | +10,000,000 | 5.1% |
| BlackRock | Mutual Fund | 2026/Q3 | +7,590,007 | 10.5% |
| Viking Global Investors LP | Hedge Fund | 2026/Q3 | +6,700,000 | 3.4% |
| RA Capital Management, L.P. | VC/PE Fund | 2026/Q3 | +6,500,000 | 3.3% |
| State Street Global Advisors | Mutual Fund | 2026/Q3 | +4,952,990 | 6.2% |
| Woodline Partners LP | Hedge Fund | 2026/Q3 | +3,400,312 | 1.7% |
| Vanguard Capital Management, LLC | Mutual Fund | 2026/Q3 | +2,943,386 | 4.9% |
| Marshall Wace LLP | Hedge Fund | 2026/Q3 | +2,823,154 | 3.5% |
| Trails Edge Capital Partners, LP | Hedge Fund | 2026/Q3 | +2,660,000 | 1.4% |
| Vanguard Portfolio Management, LLC | Mutual Fund | 2026/Q3 | +1,948,263 | 3.8% |
| Geode Capital Management, LLC | Mutual Fund | 2026/Q3 | +1,904,218 | 2.6% |
| Great Point Partners, LLC | VC/PE Fund | 2026/Q3 | +1,741,232 | 0.9% |
| Weiss Asset Management, LLC | Hedge Fund | 2026/Q3 | +1,530,803 | 0.8% |
| Nantahala Capital Management, LLC | Hedge Fund | 2026/Q3 | +1,500,000 | 0.8% |
Institutional buy/sell activity by reporting period, largest moves first.
Insider transactions
| Date | Insider | Title | Transaction | Shares | Price | Held after |
|---|---|---|---|---|---|---|
| 30 Sep 2026 | Gregory Weaver | Chief Financial Officer | Derivative Exercise and Sale | -4,379 | $2.76 | 49,927 |
| 30 Sep 2026 | Gregory Weaver | Chief Financial Officer | Derivative Exercise and Retained | +10,096 | – | 49,927 |
| 30 Sep 2026 | Christophe Arbet-Engels | Chief Medical Officer | Derivative Exercise and Sale | -12,679 | $2.76 | 24,821 |
| 30 Sep 2026 | Christophe Arbet-Engels | Chief Medical Officer | Derivative Exercise and Retained | +24,821 | – | 24,821 |
| 15 Sep 2026 | Linda Richardson | Chief Commercial Officer | Derivative Exercise and Sale | -6,826 | $3.24 | 17,174 |
| 15 Sep 2026 | Linda Richardson | Chief Commercial Officer | Derivative Exercise and Retained | +17,174 | – | 17,174 |
| 12 Aug 2026 | Jerome Durso | Chairperson & CEO | Open Market Acquisition | +15,000 | $2.95 | 62,500 |
| 30 Jul 2026 | Gregory Weaver | Chief Financial Officer | Other Acquisition | +1,753 | $2.41 | 39,831 |
| 30 Jul 2026 | M. Roberts | Chief Scientific Officer | Other Acquisition | +875 | $2.41 | 113,699 |
| 30 Apr 2026 | Mitchel Sayare | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | John Gill | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Philip Hodges | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Klaus Schafer | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Catherine Sohn | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Wayne Pisano | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Diane Jorkasky | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 30 Apr 2026 | Teri Lawver | Independent Director | Other Derivative Acquisition | +48,800 | $2.82 | 48,800 |
| 5 Apr 2026 | John Gill | Independent Director | Open Market Acquisition | +9,200 | $3.41 | 21,700 |
| 31 Mar 2026 | Gregory Weaver | Chief Financial Officer | Open Market Acquisition | +10,000 | $3.15 | 38,078 |
| 31 Mar 2026 | Jerome Durso | Chairperson & CEO | Open Market Acquisition | +15,000 | $3.14 | 47,500 |
From Form 4/Form 144 filings. Negative share counts are disposals (sales, gifts, or shares withheld for taxes); positive are acquisitions.
Short interest, by report
| Report date | Shares short | % of float | Days to cover |
|---|---|---|---|
| 15 Oct 2026 | 42,233,791 | 21.7% | 10.4 |
| 30 Sep 2026 | 46,079,911 | 23.7% | 10.5 |
| 15 Sep 2026 | 51,749,756 | 26.6% | 15.4 |
| 31 Aug 2026 | 49,714,773 | 25.6% | 11.8 |
| 14 Aug 2026 | 50,972,774 | 26.2% | 11.0 |
| 31 Jul 2026 | 51,938,259 | 26.7% | 11.5 |
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