Altimmune, Inc. (ALT) shareholders
ALTNasdaqPharmaceutical PreparationsFiscal year ends December 31
$1.65+0.03 (+2.17%)
Close on Nov 13, 2026Market cap $319.98MP/E –Yield –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
77.9%
152M of 195M shares
Institutional holders
210
58 new, 18 sold out
Net institutional buying
82M
In Q2 2026
Insider trades, 12 months
14 buys · 0 sales
Net bought $452.36K
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| Chen Yu Joint filing with TCG Crossover GP II, LLC (5.00%), TCG Crossover Fund II, L.P. (5.00%) and 2 more | 20,000,000 | 9.80% | 13G (passive) | Apr 24, 2026 |
| David Kroin Joint filing with Deep Track Capital, LP (9.99%), Deep Track Biotechnology Master Fund, Ltd. (8.65%) | 19,417,221 | 9.99% | 13G (passive) | Apr 23, 2026 |
| Viking Global Opportunities Parent GP LLC Joint filing with Viking Global Investors LP (6.70%), Halvorsen Ole Andreas (6.70%) and 1 more | 13,400,000 | 6.70% | 13G (passive) | Apr 24, 2026 |
| Rajeev Shah Joint filing with RA Capital Management, L.P. (6.50%), Peter Kolchinsky (6.50%) and 1 more | 13,000,000 | 6.50% | 13G (passive) | Apr 24, 2026 |
| BlackRock, Inc. | 6,133,427 | 7.60% | 13G (passive) amendment | Jun 30, 2025 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of ALT | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| BlackRock, Inc. | 20,385,284 | 10.48% | $61.97M | +7,590,007 | 0.00% |
| Deep Track Capital, LP | 19,250,000 | 9.90% | $58.52M | New | 0.85% |
| State Street Corp | 12,098,540 | 6.22% | $36.78M | +4,952,990 | 0.00% |
| TCG Crossover Management, LLC | 10,000,000 | 5.14% | $30.40M | New | 0.73% |
| Vanguard Capital Management LLC | 8,177,752 | 4.20% | $24.86M | +2,519,703 | 0.00% |
| Vanguard Portfolio Management LLC | 7,330,265 | 3.77% | $22.28M | +1,948,263 | 0.00% |
| Marshall Wace, Llp | 6,841,055 | 3.52% | $20.80M | +2,823,154 | 0.02% |
| Viking Global Investors LP | 6,700,000 | 3.44% | $20.37M | New | 0.06% |
| Ra Capital Management, L.P. | 6,500,000 | 3.34% | $19.76M | New | 0.17% |
| Geode Capital Management, LLC | 5,011,314 | 2.58% | $15.24M | +1,904,218 | 0.00% |
| Woodline Partners LP | 3,400,312 | 1.75% | $10.34M | New | 0.03% |
| Millennium Management LLC | 3,309,122 | 1.70% | $10.06M | +50,931 | 0.00% |
| Nantahala Capital Management, LLC | 3,000,000 | 1.54% | $9.12M | New | 0.15% |
| Trails Edge Capital Partners, LP | 2,660,000 | 1.37% | $8.09M | New | 1.28% |
| Nuveen, LLC | 2,405,354 | 1.24% | $7.31M | +70,753 | 0.00% |
| Two Sigma Investments, LP | 2,381,142 | 1.22% | $7.24M | −97,758 | 0.01% |
| Goldman Sachs Group Inc | 2,214,450 | 1.14% | $6.73M | +863,801 | 0.00% |
| Great Point Partners LLC | 1,741,232 | 0.90% | $5.29M | New | 1.00% |
| Northern Trust Corp | 1,599,226 | 0.82% | $4.86M | +602,505 | 0.00% |
| Weiss Asset Management LP | 1,530,803 | 0.79% | $4.65M | New | 0.05% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 210 | 152M | 77.9% | 58 / 87 | 33 / 18 | 88M | 6M |
| Q1 2026 | 173 | 69M | 35.7% | 30 / 81 | 35 / 35 | 34M | 10M |
| Q4 2025 | 183 | 55M | 28.4% | 49 / 73 | 29 / 21 | 18M | 4M |
| Q3 2025 | 158 | 42M | 21.4% | 23 / 57 | 48 / 42 | 10M | 6M |
| Q2 2025 | 180 | 38M | 19.4% | 38 / 71 | 41 / 34 | 8M | 9M |
| Q1 2025 | 177 | 38M | 19.6% | 27 / 54 | 52 / 29 | 6M | 8M |
| Q4 2024 | 182 | 41M | 20.9% | 38 / 64 | 45 / 23 | 5M | 4M |
| Q3 2024 | 169 | 40M | 20.4% | 22 / 59 | 46 / 25 | 9M | 7M |
| Q2 2024 | 173 | 43M | 22.0% | 45 / 53 | 47 / 40 | 13M | 19M |
| Q1 2024 | 171 | 49M | 25.2% | 59 / 51 | 38 / 30 | 24M | 10M |
| Q4 2023 | 143 | 35M | 17.8% | 56 / 41 | 24 / 25 | 16M | 12M |
| Q3 2023 | 112 | 30M | 15.6% | 16 / 27 | 40 / 23 | 2M | 7M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
135 funds held ALT in Q2 2026, 65% of their shares through ETFs. Each fund counts once per quarter, from its quarter-end report.
| Fund | Shares | % of ALT | Value | % of fund | As of |
|---|---|---|---|---|---|
| State Street(R) SPDR(R) S&P(R) Biotech ETF | 8,096,724 | 4.16% | $24.61M | 0.23% | Jun 30, 2026 |
| Vanguard Total Stock Market Index Fund | 5,748,771 | 2.96% | $17.48M | 0.00% | Jun 30, 2026 |
| iShares Russell 2000 ETF | 5,161,850 | 2.65% | $15.69M | 0.02% | Jun 30, 2026 |
| Vanguard Strategic Equity Fund | 2,519,635 | 1.30% | $7.66M | 0.06% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 2,236,217 | 1.15% | $6.80M | 0.01% | Jun 30, 2026 |
| Fidelity Small Cap Index Fund | 2,173,494 | 1.12% | $6.17M | 0.02% | Jul 31, 2026 |
| iShares Russell 2000 Value ETF | 1,869,684 | 0.96% | $5.68M | 0.04% | Jun 30, 2026 |
| iShares Biotechnology ETF | 1,295,713 | 0.67% | $3.94M | 0.04% | Jun 30, 2026 |
| Vanguard Explorer Fund | 1,213,513 | 0.62% | $3.45M | 0.02% | Jul 31, 2026 |
| BlackRock Advantage Small Cap Core Fund | 1,045,359 | 0.54% | $3.19M | 0.06% | May 29, 2026 |
| Fidelity Extended Market Index Fund | 988,478 | 0.51% | $3.01M | 0.01% | May 31, 2026 |
| Vanguard Strategic Small-Cap Equity Fund | 867,177 | 0.45% | $2.64M | 0.08% | Jun 30, 2026 |
| Vanguard Russell 2000 Index Fund | 670,084 | 0.34% | $2.04M | 0.01% | May 31, 2026 |
| iShares Micro-Cap ETF | 668,001 | 0.34% | $2.03M | 0.13% | Jun 30, 2026 |
| Fidelity Enhanced Small Cap Core ETF | 638,025 | 0.33% | $1.94M | 0.03% | Jun 30, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Jerome Benedict Durso | President and CEO, Director | 93,200 | 0.05% | Nov 13, 2026 |
| Gregory L. Weaver | Chief Financial Officer | 73,005 | 0.04% | Nov 13, 2026 |
| Christophe Arbet-Engels | Chief Medical Officer | 24,821 | 0.01% | Oct 5, 2026 |
| Richard Thomas Menziuso | Principal Accounting Officer | – | – | Oct 2, 2026 |
| Linda M. Richardson | Chief Commercial Officer | 24,000 | 0.01% | Sep 17, 2026 |
| M. Scot Roberts | Chief Scientific Officer | 113,714 | 0.06% | Aug 3, 2026 |
| Raymond M. Jordt | Chief Business Officer | 70,107 | 0.04% | Feb 2, 2026 |
| Matthew Scott Harris | Chief Medical Officer | 83,874 | 0.04% | Aug 4, 2025 |
| Wayne Pisano | Director | 58,800 | 0.03% | Nov 13, 2026 |
| Peter Greenleaf | Director | – | – | Nov 4, 2026 |
| Alex G. Howarth | Director | – | – | Nov 4, 2026 |
| Philip Hodges | Director | 26,579 | 0.01% | May 1, 2026 |
| Klaus Schafer | Director | 8,960 | 0.00% | May 1, 2026 |
| Catherine A. Sohn | Director | 1,500 | 0.00% | May 1, 2026 |
| Diane Jorkasky | Director | 527 | 0.00% | May 1, 2026 |
| John Gill | Director | 21,700 | 0.01% | May 1, 2026 |
| Teri L. Lawver | Director | – | – | May 1, 2026 |
| Mitchel Sayare | Director | 59,013 | 0.03% | May 1, 2026 |
| Vipin K. Garg | Director | 424,519 | 0.22% | Feb 2, 2026 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Gregory L. Weaver Chief Financial Officer | Nov 13, 2026 | Buy | +10,000 | $1.62 | $16.20K | 73,005 |
| Wayne Pisano Director | Nov 13, 2026 | Buy | +10,000 | $1.64 | $16.35K | 58,800 |
| Jerome Benedict Durso President and CEO, Director | Nov 13, 2026 | Buy | +30,700 | $1.62 | $49.69K | 93,200 |
| Gregory L. Weaver Chief Financial Officer | Nov 11, 2026 | Tax withholding | −5,672 | $1.93 | $10.95K | 63,005 |
| Gregory L. Weaver Chief Financial Officer | Nov 11, 2026 | Option exercise | +18,750 | – | – | 68,677 |
| Christophe Arbet-Engels Chief Medical Officer | Oct 1, 2026 | Tax withholding | −12,679 | $2.76 | $34.99K | 24,821 |
| Christophe Arbet-Engels Chief Medical Officer | Oct 1, 2026 | Option exercise | +37,500 | – | – | 37,500 |
| Gregory L. Weaver Chief Financial Officer | Oct 1, 2026 | Tax withholding | −4,379 | $2.76 | $12.09K | 49,927 |
| Gregory L. Weaver Chief Financial Officer | Oct 1, 2026 | Option exercise | +14,475 | – | – | 54,306 |
| Linda M. Richardson Chief Commercial Officer | Sep 16, 2026 | Option exercise | +24,000 | – | – | 24,000 |
| Linda M. Richardson Chief Commercial Officer | Sep 16, 2026 | Tax withholding | −6,826 | $3.24 | $22.12K | 17,174 |
| Jerome Benedict Durso President and CEO, Director | Aug 13, 2026 | Buy | +15,000 | $2.95 | $44.25K | 62,500 |
| Gregory L. Weaver Chief Financial Officer | Jul 31, 2026 | Award | +1,753 | $2.41 | $4.22K | 39,831 |
| M. Scot Roberts Chief Scientific Officer | Jul 31, 2026 | Award | +875 | $2.41 | $2.11K | 113,699 |
| John Gill Director | Apr 6, 2026 | Buy | +9,200 | $3.41 | $31.37K | 21,700 |
| Gregory L. Weaver Chief Financial Officer | Apr 1, 2026 | Buy | +10,000 | $3.15 | $31.50K | 38,078 |
| Jerome Benedict Durso President and CEO, Director | Apr 1, 2026 | Buy | +15,000 | $3.14 | $47.10K | 47,500 |
| Gregory L. Weaver Chief Financial Officer | Mar 6, 2026 | Buy | +5,000 | $3.54 | $17.70K | 28,078 |
| Jerome Benedict Durso President and CEO, Director | Mar 6, 2026 | Buy | +20,000 | $3.54 | $70.80K | 32,500 |
| M. Scot Roberts Chief Scientific Officer | Feb 2, 2026 | Tax withholding | −2,329 | $5.55 | $12.93K | 112,824 |
| M. Scot Roberts Chief Scientific Officer | Feb 2, 2026 | Option exercise | +7,775 | – | – | 115,153 |
| M. Scot Roberts Chief Scientific Officer | Jan 31, 2026 | Award | +5,567 | $3.07 | $17.09K | 107,378 |
| Raymond M. Jordt Chief Business Officer | Jan 31, 2026 | Award | +4,571 | $3.07 | $14.03K | 70,107 |
| Vipin K. Garg Director | Jan 31, 2026 | Award | +6,926 | $3.07 | $21.26K | 424,519 |
| M. Scot Roberts Chief Scientific Officer | Jan 30, 2026 | Tax withholding | −2,859 | $5.60 | $16.01K | 101,811 |
| M. Scot Roberts Chief Scientific Officer | Jan 30, 2026 | Option exercise | +9,275 | – | – | 104,670 |
| Vipin K. Garg Director | Jan 30, 2026 | Option exercise | +26,775 | – | – | 429,225 |
| Vipin K. Garg Director | Jan 30, 2026 | Tax withholding | −11,632 | $5.60 | $65.14K | 417,593 |
| M. Scot Roberts Chief Scientific Officer | Jan 27, 2026 | Option exercise | +15,850 | – | – | 100,143 |
| M. Scot Roberts Chief Scientific Officer | Jan 27, 2026 | Tax withholding | −4,748 | $6.18 | $29.34K | 95,395 |
| Raymond M. Jordt Chief Business Officer | Jan 27, 2026 | Tax withholding | −4,229 | $6.18 | $26.14K | 65,536 |
| Raymond M. Jordt Chief Business Officer | Jan 27, 2026 | Option exercise | +15,850 | – | – | 69,765 |
| Vipin K. Garg Director | Jan 27, 2026 | Tax withholding | −17,898 | $6.18 | $110.61K | 402,450 |
| Vipin K. Garg Director | Jan 27, 2026 | Option exercise | +41,200 | – | – | 420,348 |
| M. Scot Roberts Chief Scientific Officer | Jan 25, 2026 | Tax withholding | −4,373 | $5.50 | $24.05K | 84,293 |
| M. Scot Roberts Chief Scientific Officer | Jan 25, 2026 | Option exercise | +14,600 | – | – | 88,666 |
| Vipin K. Garg Director | Jan 25, 2026 | Tax withholding | −17,984 | $5.50 | $98.91K | 379,148 |
| Vipin K. Garg Director | Jan 25, 2026 | Option exercise | +42,050 | – | – | 397,132 |
| Raymond M. Jordt Chief Business Officer | Jan 25, 2026 | Tax withholding | −3,855 | $5.50 | $21.20K | 53,915 |
| Raymond M. Jordt Chief Business Officer | Jan 25, 2026 | Option exercise | +14,600 | – | – | 57,770 |
| Wayne Pisano Director | Jan 8, 2026 | Buy | +5,000 | $4.08 | $20.40K | 13,498 |
| Catherine A. Sohn Director | Jan 5, 2026 | Buy | +500 | $4.24 | $2.12K | 1,500 |
| Raymond M. Jordt Chief Business Officer | Jan 1, 2026 | Tax withholding | −2,475 | $3.61 | $8.93K | 43,170 |
| Raymond M. Jordt Chief Business Officer | Jan 1, 2026 | Option exercise | +9,375 | – | – | 45,645 |
| Diane Jorkasky Director | Dec 29, 2025 | Buy | +527 | $3.80 | $2.00K | 527 |
| John Gill Director | Dec 23, 2025 | Buy | +12,500 | $4.10 | $51.25K | 12,500 |
| Jerome Benedict Durso Director | Dec 22, 2025 | Buy | +12,500 | $4.13 | $51.63K | 12,500 |
| Gregory L. Weaver Chief Financial Officer | Nov 11, 2025 | Option exercise | +18,750 | – | – | 28,750 |
| Gregory L. Weaver Chief Financial Officer | Nov 11, 2025 | Tax withholding | −5,672 | $4.28 | $24.28K | 23,078 |
| M. Scot Roberts Chief Scientific Officer | Jul 31, 2025 | Award | +846 | $3.14 | $2.66K | 74,066 |
| Matthew Scott Harris Chief Medical Officer | Jul 31, 2025 | Award | +2,018 | $3.14 | $6.34K | 16,087 |
| Raymond M. Jordt Chief Business Officer | Jul 31, 2025 | Award | +1,368 | $3.14 | $4.30K | 36,270 |
| Catherine A. Sohn Director | Mar 17, 2025 | Buy | +1,000 | $5.78 | $5.78K | 1,000 |
| Gregory L. Weaver Chief Financial Officer | Mar 13, 2025 | Buy | +10,000 | $5.20 | $52.00K | 10,000 |
| Matthew Scott Harris Chief Medical Officer | Mar 7, 2025 | Gift | −67,787 | – | – | 14,069 |
| Vipin K. Garg President and CEO, Director | Feb 2, 2025 | Option exercise | +18,950 | – | – | 363,364 |
| Vipin K. Garg President and CEO, Director | Feb 2, 2025 | Tax withholding | −8,282 | $6.64 | $54.99K | 355,082 |
| M. Scot Roberts Chief Scientific Officer | Feb 2, 2025 | Option exercise | +7,775 | – | – | 75,536 |
| M. Scot Roberts Chief Scientific Officer | Feb 2, 2025 | Tax withholding | −2,316 | $6.64 | $15.38K | 73,220 |
| Matthew Scott Harris Chief Medical Officer | Feb 2, 2025 | Option exercise | +7,775 | – | – | 84,564 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Short interest
Shares sold short and not yet bought back, as of Oct 30, 2026 (FINRA, reported twice a month)
Short % of float
21.77%
42M shares short
Days to cover
12.2
At 3M shares a day
Change since last report
-0.2%
From 42M shares
Short volume, 20 days
57.8%
Of volume reported to FINRA
Shares sold short, last 12 months
Short sale volume counts trades marked short on any given day, including market-maker hedging, so it runs far higher than the share of Altimmune's stock actually held short. Settlement fails (shares not delivered on time) peaked at 61,991 shares on Aug 24, 2026 over the last 90 days.
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