ALTIMMUNE INC ALT
COM NEW · Common Stock · CUSIP 02155H200 · ISIN US02155H2004
American biopharmaceutical company
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersGaithersburg, MD
- Founded1997
- Websitealtimmune.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($65.9k this quarter). Holder counts are more reliable. Shares outstanding: 194.5m as of 2026-08-07, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $3.04. Options: 10 managers hold calls ($14.4m notional), 6 hold puts ($2.1m).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 122 |
| Q4 2022 | 129 |
| Q1 2023 | 134 |
| Q2 2023 | 120 |
| Q3 2023 | 113 |
| Q4 2023 | 143 |
| Q1 2024 | 171 |
| Q2 2024 | 173 |
| Q3 2024 | 169 |
| Q4 2024 | 182 |
| Q1 2025 | 178 |
| Q2 2025 | 181 |
| Q3 2025 | 158 |
| Q4 2025 | 184 |
| Q1 2026 | 173 |
| Q2 2026 | 210 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 79 | 71 |
| Q4 2024 | 90 | 68 |
| Q1 2025 | 80 | 78 |
| Q2 2025 | 108 | 75 |
| Q3 2025 | 79 | 89 |
| Q4 2025 | 117 | 50 |
| Q1 2026 | 106 | 71 |
| Q2 2026 | 144 | 51 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $19.2m | $14.1m | 0.73 |
| Q4 2025 | $13.4m | $15.7m | 1.18 |
| Q1 2026 | $10.4m | $3.2m | 0.31 |
| Q2 2026 | $14.4m | $2.1m | 0.15 |
Biggest buyers
| Deep Track Capital, LP | New | +19.2m |
| TCG Crossover Management, LLC | New | +10.0m |
| BlackRock, Inc. | Added | +7.6m |
| VIKING GLOBAL INVESTORS LP | New | +6.7m |
| RA CAPITAL MANAGEMENT, L.P. | New | +6.5m |
| STATE STREET CORP | Added | +5.0m |
| Woodline Partners LP | New | +3.4m |
| Nantahala Capital Management, LLC | New | +3.0m |
| MARSHALL WACE, LLP | Added | +2.8m |
| Trails Edge Capital Partners, LP | New | +2.7m |
Biggest sellers
| Alyeska Investment Group, L.P. | Sold out | -2.6m |
| SCHRODER INVESTMENT MANAGEMENT GROUP | Sold out | -667.8k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | -594.9k |
| D. E. Shaw & Co., Inc. | Reduced | -525.4k |
| DIMENSIONAL FUND ADVISORS LP | Reduced | -406.5k |
| Point72 Asset Management, L.P. | Reduced | -178.4k |
| TWO SIGMA INVESTMENTS, LP | Reduced | -97.8k |
| HSBC HOLDINGS PLC | Reduced | -89.9k |
| Engineers Gate Manager LP | Reduced | -78.1k |
| Virtu Financial LLC | Sold out | -70.5k |
Biggest calls
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $5.5m1.8m shares |
| GROUP ONE TRADING LLC | Added | $3.5m1.2m shares |
| CITADEL ADVISORS LLC | Added | $1.9m631.0k shares |
| SIMPLEX TRADING, LLC | Added | $1.4m468.6k shares |
| IMC-Chicago, LLC | Added | $1.2m394.0k shares |
| JANE STREET GROUP, LLC | Reduced | $691.3k227.4k shares |
| DCF Advisers, LLC | Unchanged | $112.5k37.0k shares |
| Walleye Capital LLC | Added | $41.0k13.5k shares |
| Advisory Services Network, LLC | New | $13.7k4.5k shares |
| HUB Investment Partners, LLC | Reduced | $9.1k3.0k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $990.1k325.7k shares |
| CITADEL ADVISORS LLC | Reduced | $389.1k128.0k shares |
| GROUP ONE TRADING LLC | Reduced | $309.8k101.9k shares |
| JANE STREET GROUP, LLC | Reduced | $150.2k49.4k shares |
| SIMPLEX TRADING, LLC | Reduced | $138.9k45.7k shares |
| IMC-Chicago, LLC | Reduced | $114.3k37.6k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| Deep Track Capital, LP 13G · passive investor new · filed 2026-04-30 | 10.0% |
| TCG Crossover GP II, LLC 13G · passive investor new · filed 2026-05-01 | 9.8% |
| BlackRock, Inc. 13G · institution -1.1 pts · filed 2025-07-16 | 7.6% |
| VIKING GLOBAL INVESTORS LP 13G · passive investor new · filed 2026-05-01 | 6.7% |
| RA CAPITAL MANAGEMENT, L.P. 13G · passive investor new · filed 2026-05-01 | 6.5% |
| STATE STREET CORP 13G · institution new · filed 2026-05-12 | 5.5% |
Fell to 5% or below in the last year: TANG CAPITAL MANAGEMENT LLC (0.3%, 2026-05-15), VANGUARD GROUP INC (0.0%, 2026-03-26)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 0 | — | — |
| Q1 2025 | 2 | $57.8k | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 3 | $104.9k | 0 | — | — |
| Q1 2026 | 4 | $111.0k | 0 | — | — |
| Q2 2026 | 3 | $110.0k | 0 | — | — |
| Q3 2026 | 1 | $44.2k | 0 | — | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-08-13 | Durso Jerome Benedict President and CEO, director | Bought | $44.2k15.0k shares |
| 2026-04-06 | GILL JOHN Director | Bought | $31.4k9.2k shares |
| 2026-04-01 | Durso Jerome Benedict President and CEO, director | Bought | $47.1k15.0k shares |
| 2026-04-01 | WEAVER GREGORY L Chief Financial Officer | Bought | $31.5k10.0k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 20.4m $62.0m | Added +7.6m |
| Deep Track Capital, LP 0.86% of their portfolio | 19.2m $58.5m | New |
| STATE STREET CORP 0.00% of their portfolio | 12.1m $36.8m | Added +5.0m |
| TCG Crossover Management, LLC 0.73% of their portfolio | 10.0m $30.4m | New |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 8.2m $24.9m | Added +2.5m |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 7.3m $22.3m | Added +1.9m |
| MARSHALL WACE, LLP 0.02% of their portfolio | 6.8m $20.8m | Added +2.8m |
| VIKING GLOBAL INVESTORS LP 0.06% of their portfolio | 6.7m $20.4m | New |
| RA CAPITAL MANAGEMENT, L.P. 0.17% of their portfolio | 6.5m $19.8m | New |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 5.0m $15.2m | Added +1.9m |
| Woodline Partners LP 0.03% of their portfolio | 3.4m $10.3m | New |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 3.3m $10.1m | Added +50.9k |
| Nantahala Capital Management, LLC 0.28% of their portfolio | 3.0m $9.1m | New |
| Trails Edge Capital Partners, LP 1.28% of their portfolio | 2.7m $8.1m | New |
| Nuveen, LLC 0.00% of their portfolio | 2.4m $7.3m | Added +70.8k |
| TWO SIGMA INVESTMENTS, LP 0.01% of their portfolio | 2.4m $7.2m | Reduced -97.8k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 2.2m $6.7m | Added +863.8k |
| GREAT POINT PARTNERS LLC 1.25% of their portfolio | 1.7m $5.3m | New |
| NORTHERN TRUST CORP 0.00% of their portfolio | 1.6m $4.9m | Added +602.5k |
| Weiss Asset Management LP 0.05% of their portfolio | 1.5m $4.7m | Not comparable |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 1.3m $3.9m | Added +423.7k |
| Cormorant Asset Management, LP 0.19% of their portfolio | 1.2m $3.8m | New |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 1.2m $3.7m | Added +1.1m |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 983.6k $3.0m | Added +534.7k |
| UBS Group AG 0.00% of their portfolio | 866.4k $2.6m | Reduced -38.4k |
| MORGAN STANLEY 0.00% of their portfolio | 758.4k $2.3m | Reduced -16.8k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 757.9k $2.3m | Added +187.7k |
| Ghisallo Capital Management LLC 0.04% of their portfolio | 750.0k $2.3m | New |
| FMR LLC 0.00% of their portfolio | 749.0k $2.3m | Added +75.0k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 731.1k $2.2m | Reduced -594.9k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 689.7k $2.1m | Added +276.2k |
| TANG CAPITAL MANAGEMENT LLC 0.09% of their portfolio | 666.0k $2.0m | Unchanged |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 639.4k $1.9m | Reduced -406.5k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 624.5k $1.9m | Added +272.8k |
| Hennion & Walsh Asset Management, Inc. 0.04% of their portfolio | 518.2k $1.6m | Added +316.2k |
| Point72 Asset Management, L.P. 0.00% of their portfolio | 486.9k $1.5m | Reduced -178.4k |
| Rock Springs Capital Management LP 0.07% of their portfolio | 471.5k $1.4m | New |
| Beirne Wealth Consulting Services, LLC 0.26% of their portfolio | 421.9k $1.3m | Added +10.0k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 420.3k $1.3m | Added +172.1k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 371.2k $1.1m | Reduced -63.9k |
| BARCLAYS PLC 0.00% of their portfolio | 351.6k $1.1m | Added +158.7k |
| Invesco Ltd. 0.00% of their portfolio | 332.6k $1.0m | Added +104.7k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 309.6k $941.2k | Added +153.9k |
| Janney Montgomery Scott LLC 0.00% of their portfolio | 302.6k $920.0k | Added +130.0k |
| LMR Partners LLP 0.01% of their portfolio | 300.0k $912.0k | New |
| CITIGROUP INC 0.00% of their portfolio | 293.9k $893.6k | Added +217.6k |
| Steward Partners Investment Advisory, LLC 0.00% of their portfolio | 266.7k $810.7k | Added +14.9k |
| MANGROVE PARTNERS IM, LLC 0.05% of their portfolio | 239.3k $727.4k | Unchanged |
| Baird Financial Group, Inc. 0.00% of their portfolio | 237.5k $722.1k | Unchanged |
| BROWN WEALTH MANAGEMENT, LLC 0.16% of their portfolio | 236.1k $717.9k | Unchanged |
| Rafferty Asset Management, LLC 0.00% of their portfolio | 225.1k $684.2k | Reduced -6.2k |
| Creative Planning 0.00% of their portfolio | 218.3k $663.6k | Added +179.1k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 217.4k $661.0k | Added +121.5k |
| COMMONWEALTH EQUITY SERVICES, LLC 0.00% of their portfolio | 214.6k $652.3k | Added +54.2k |
| Squarepoint Ops LLC 0.00% of their portfolio | 202.4k $615.2k | Added +184.3k |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 201.6k $613.0k | Reduced -525.4k |
| ALPS ADVISORS INC 0.00% of their portfolio | 197.4k $600.0k | Added +91.5k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 195.0k $592.8k | Added +70.5k |
| STIFEL FINANCIAL CORP 0.00% of their portfolio | 192.4k $584.8k | Added +57.8k |
| Jump Financial, LLC 0.01% of their portfolio | 190.0k $577.6k | New |
| Man Group plc 0.00% of their portfolio | 173.9k $528.6k | Added +44.0k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 165.4k $503.0k | Added +72.9k |
| Knoll Capital Management, LLC 0.27% of their portfolio | 160.0k $486.4k | Unchanged |
| Birchview Capital, LP 0.22% of their portfolio | 152.7k $464.1k | New |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 140.8k $433.8k | Added +69.1k |
| Brevan Howard Capital Management LP 0.01% of their portfolio | 130.8k $397.6k | Added +52.4k |
| XTX Topco Ltd 0.01% of their portfolio | 128.1k $389.4k | New |
| Virtus Investment Advisers, LLC 0.09% of their portfolio | 125.4k $381.1k | Added +73.6k |
| WEALTH EFFECTS LLC 0.10% of their portfolio | 122.7k $372.9k | Reduced -9.3k |
| LPL Financial LLC 0.00% of their portfolio | 122.0k $370.7k | Added +18.2k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 117.7k $355.1k | Added +40.4k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 116.9k $355.2k | Added +44.6k |
| PROFUND ADVISORS LLC 0.01% of their portfolio | 113.6k $345.3k | Added +10.5k |
| Jefferies Financial Group Inc. 0.00% of their portfolio | 110.0k $334.4k | Unchanged |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 106.6k $313.5k | Reduced -20.9k |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.00% of their portfolio | 103.5k $314.6k | Unchanged |
| Susquehanna Portfolio Strategies, LLC 0.01% of their portfolio | 103.4k $314.3k | New |
| Summit Financial Wealth Advisors, LLC 0.04% of their portfolio | 103.3k $314.0k | Unchanged |
| ADAR1 Capital Management, LLC 0.01% of their portfolio | 102.8k $312.6k | New |
| Mariner, LLC 0.00% of their portfolio | 101.1k $307.4k | New |
| NOMURA ASSET MANAGEMENT INTERNATIONAL INC. 0.00% of their portfolio | 100.0k $304.0k | Unchanged |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 87.3k $265.4k | Added +34.0k |
| Grantham, Mayo, Van Otterloo & Co. LLC 0.00% of their portfolio | 83.8k $254.9k | Reduced -42.6k |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 75.0k $228.1k | Added +32.2k |
| KINGSWOOD WEALTH ADVISORS, LLC 0.01% of their portfolio | 74.5k $226.5k | Reduced -2.0k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 71.6k $217.7k | New |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 68.6k $208.5k | Reduced -3.4k |
| IEQ CAPITAL, LLC 0.00% of their portfolio | 67.0k $203.5k | New |
| PVG ASSET MANAGEMENT CORP 0.12% of their portfolio | 66.1k $201.0k | Unchanged |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 64.5k $199.5k | Reduced -89.9k |
| Leonteq Securities AG 0.01% of their portfolio | 64.0k $194.6k | Reduced -1.0k |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 58.6k $178.2k | Added +23.2k |
| AXQ CAPITAL, LP 0.02% of their portfolio | 56.8k $172.7k | Added +9.1k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 56.7k $172.5k | New |
| Corient Private Wealth LP 0.00% of their portfolio | 54.2k $164.8k | Added +23.7k |
| MERCER GLOBAL ADVISORS INC /ADV 0.00% of their portfolio | 53.1k $161.5k | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 52.7k $160.4k | Added +31.3k |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 52.0k $158.2k | Added +17.3k |
| Cetera Investment Advisers 0.00% of their portfolio | 51.9k $157.8k | Added +16.4k |
| Rockefeller Capital Management L.P. 0.00% of their portfolio | 49.7k $151.2k | Added +3.4k |