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 ($75.2k this quarter). Holder counts are more reliable. Shares outstanding: 88.3m as of 2025-08-08, 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 ≈ $3.87. Options: 24 managers hold calls ($26.3m notional), 21 hold puts ($22.6m).
Trends to Q2 2025
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 |
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 2023 | 43 | 62 |
| Q4 2023 | 91 | 50 |
| Q1 2024 | 108 | 68 |
| Q2 2024 | 95 | 86 |
| Q3 2024 | 79 | 71 |
| Q4 2024 | 90 | 68 |
| Q1 2025 | 80 | 78 |
| Q2 2025 | 108 | 75 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2024 | $11.8m | $8.5m | 0.72 |
| Q4 2024 | $23.0m | $16.1m | 0.70 |
| Q1 2025 | $13.5m | $10.3m | 0.76 |
| Q2 2025 | $26.3m | $22.6m | 0.86 |
Biggest buyers
| Caption Management, LLC | Added | +941.9k |
| VANGUARD GROUP INC | Added | +759.7k |
| FEDERATED HERMES, INC. | Added | +727.7k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | +543.7k |
| CITADEL ADVISORS LLC | New | +523.5k |
| BANK OF AMERICA CORP /DE/ | Added | +435.5k |
| FMR LLC | Added | +381.0k |
| Virtu Financial LLC | New | +267.8k |
| Scientech Research LLC | New | +254.3k |
| Caitong International Asset Management Co., Ltd | Added | +238.7k |
Biggest sellers
| AMERIPRISE FINANCIAL INC | Reduced | -1.3m |
| MARSHALL WACE, LLP | Reduced | -1.1m |
| Bellevue Group AG | Sold out | -1.1m |
| MILLENNIUM MANAGEMENT LLC | Reduced | -1.0m |
| SCHRODER INVESTMENT MANAGEMENT GROUP | Sold out | -961.9k |
| TWO SIGMA INVESTMENTS, LP | Reduced | -710.5k |
| STATE STREET CORP | Reduced | -637.9k |
| RFG Advisory, LLC | Sold out | -324.4k |
| JANE STREET GROUP, LLC | Sold out | -152.6k |
| Swiss National Bank | Sold out | -139.5k |
Biggest calls
| DIADEMA PARTNERS LP | Added | $4.9m1.3m shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $4.3m1.1m shares |
| SIMPLEX TRADING, LLC | Added | $3.2m832.1k shares |
| Ikarian Capital, LLC | New | $3.2m827.5k shares |
| GROUP ONE TRADING LLC | Added | $2.3m607.1k shares |
| IMC-Chicago, LLC | Added | $1.6m419.6k shares |
| Caption Management, LLC | Reduced | $1.2m322.8k shares |
| BOOTHBAY FUND MANAGEMENT, LLC | New | $1.2m301.1k shares |
| CITADEL ADVISORS LLC | Reduced | $1.0m260.7k shares |
| Affinity Asset Advisors, LLC | New | $774.0k200.0k shares |
Biggest puts
| Caption Management, LLC | Added | $5.2m1.3m shares |
| CITADEL ADVISORS LLC | Added | $3.4m886.4k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $3.3m859.5k shares |
| GROUP ONE TRADING LLC | Added | $2.5m652.3k shares |
| IMC-Chicago, LLC | Added | $1.4m364.9k shares |
| LMR Partners LLP | New | $1.4m352.8k shares |
| SIMPLEX TRADING, LLC | Added | $1.3m341.8k shares |
| Persistent Asset Partners Ltd | New | $792.4k19.1k shares |
| DIADEMA PARTNERS LP | New | $663.3k171.4k shares |
| Sculptor Capital LP | Added | $584.4k151.0k 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 in Q2 2025
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 |
|---|---|---|---|---|---|
| Q3 2023 | 1 | $864 | 0 | — | — |
| Q4 2023 | 0 | — | 0 | — | — |
| Q1 2024 | 0 | — | 0 | — | — |
| Q2 2024 | 0 | — | 0 | — | — |
| Q3 2024 | 0 | — | 1 | $110.5k | — |
| Q4 2024 | 0 | — | 0 | — | — |
| Q1 2025 | 2 | $57.8k | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
None reported in Q2 2025.
Holders, Q2 2025
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 6.4m $24.7m | Added +237.3k |
| VANGUARD GROUP INC 0.00% of their portfolio | 5.2m $20.0m | Added +759.7k |
| STATE STREET CORP 0.00% of their portfolio | 2.8m $10.7m | Reduced -637.9k |
| TANG CAPITAL MANAGEMENT LLC 0.54% of their portfolio | 2.8m $10.6m | Unchanged |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 1.9m $7.5m | Added +229.0k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.01% of their portfolio | 1.6m $6.3m | Added +543.7k |
| Knoll Capital Management, LLC 3.09% of their portfolio | 1.1m $4.3m | Unchanged |
| Caption Management, LLC 0.35% of their portfolio | 980.8k $3.8m | Added +941.9k |
| FEDERATED HERMES, INC. 0.01% of their portfolio | 915.5k $3.5m | Added +727.7k |
| UBS Group AG 0.00% of their portfolio | 886.9k $3.4m | Added +98.8k |
| MORGAN STANLEY 0.00% of their portfolio | 835.4k $3.2m | Added +178.2k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 716.0k $2.8m | Added +435.5k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 640.3k $2.5m | Added +3.6k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 523.5k $2.0m | New |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 499.2k $1.9m | Added +108.9k |
| GROUP ONE TRADING LLC 0.06% of their portfolio | 469.4k $1.8m | Added +212.8k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 447.5k $1.7m | Reduced -45.0k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 437.3k $1.7m | Reduced -710.5k |
| FMR LLC 0.00% of their portfolio | 401.8k $1.6m | Added +381.0k |
| Beirne Wealth Consulting Services, LLC 0.43% of their portfolio | 342.5k $1.3m | Added +48.0k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 332.0k $1.3m | Added +143.0k |
| BARCLAYS PLC 0.00% of their portfolio | 292.1k $1.1m | Added +104.6k |
| Virtu Financial LLC 0.05% of their portfolio | 267.8k $1.0m | New |
| Scientech Research LLC 0.24% of their portfolio | 254.3k $984.2k | New |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 251.9k $974.7k | Added +26.9k |
| Caitong International Asset Management Co., Ltd 0.66% of their portfolio | 239.6k $927.4k | Added +238.7k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 233.5k $903.7k | Added +21.6k |
| BROWN WEALTH MANAGEMENT, LLC 0.28% of their portfolio | 231.1k $894.3k | Added +131.1k |
| Steward Partners Investment Advisory, LLC 0.01% of their portfolio | 213.4k $825.8k | Added +64.2k |
| GERBER, LLC 0.56% of their portfolio | 206.8k $800.2k | Reduced -75.0k |
| Nuveen, LLC 0.00% of their portfolio | 202.4k $783.1k | Reduced -61.5k |
| Hennion & Walsh Asset Management, Inc. 0.03% of their portfolio | 189.0k $731.3k | Reduced -8.7k |
| IMC-Chicago, LLC 0.02% of their portfolio | 186.8k $723.0k | Added +103.5k |
| EXCHANGE TRADED CONCEPTS, LLC 0.01% of their portfolio | 175.7k $680.0k | Added +22.1k |
| Moody Aldrich Partners LLC 0.12% of their portfolio | 157.6k $610.0k | New |
| Sculptor Capital LP 0.01% of their portfolio | 151.0k $584.4k | Added +63.0k |
| INTECH INVESTMENT MANAGEMENT LLC 0.01% of their portfolio | 144.9k $560.7k | Added +73.5k |
| Woodline Partners LP 0.00% of their portfolio | 142.9k $552.9k | New |
| Brevan Howard Capital Management LP 0.01% of their portfolio | 133.2k $515.5k | Added +89.4k |
| TWO SIGMA ADVISERS, LP 0.00% of their portfolio | 129.2k $500.0k | Reduced -135.1k |
| Summit Financial Wealth Advisors, LLC 0.09% of their portfolio | 123.0k $476.0k | Added +5.0k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 121.9k $472.0k | Added +69.5k |
| GSA CAPITAL PARTNERS LLP 0.03% of their portfolio | 121.4k $470.0k | Added +90.6k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 114.0k $441.1k | Added +7.5k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 113.9k $440.7k | Reduced -1.3m |
| Invesco Ltd. 0.00% of their portfolio | 106.9k $413.6k | Added +25.7k |
| Avidity Partners Management LP 0.08% of their portfolio | 105.0k $406.4k | New |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 104.7k $405.2k | Reduced -5.8k |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.00% of their portfolio | 103.5k $400.5k | Unchanged |
| Rafferty Asset Management, LLC 0.00% of their portfolio | 102.0k $394.8k | Reduced -41.7k |
| MACQUARIE GROUP LTD 0.00% of their portfolio | 100.0k $387.0k | Unchanged |
| SIMPLEX TRADING, LLC 0.01% of their portfolio | 100.0k $386.0k | Added +79.1k |
| COMMONWEALTH EQUITY SERVICES, LLC 0.00% of their portfolio | 98.9k $383.0k | Added +9.2k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 98.4k $380.7k | Added +6.7k |
| Centiva Capital, LP 0.02% of their portfolio | 92.3k $357.3k | New |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 85.5k $328.6k | Added +13.2k |
| Susquehanna Portfolio Strategies, LLC 0.01% of their portfolio | 84.3k $326.4k | New |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 78.3k $303.0k | Reduced -1.0m |
| LPL Financial LLC 0.00% of their portfolio | 75.5k $292.2k | Added +8.9k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 71.8k $277.7k | Unchanged |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 70.8k $273.9k | Reduced -9.1k |
| CITIGROUP INC 0.00% of their portfolio | 68.2k $263.9k | Reduced -95.3k |
| Baird Financial Group, Inc. 0.00% of their portfolio | 59.4k $230.0k | Unchanged |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 51.3k $198.4k | Added +742 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 47.3k $181.4k | Reduced -1.6k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 46.9k $181.4k | Unchanged |
| WOLVERINE TRADING, LLC 0.00% of their portfolio | 45.5k $159.3k | New |
| STIFEL FINANCIAL CORP 0.00% of their portfolio | 41.6k $160.8k | Added +5.1k |
| AXQ CAPITAL, LP 0.05% of their portfolio | 41.3k $159.8k | New |
| Creative Planning 0.00% of their portfolio | 41.2k $159.3k | Added +9.6k |
| MML INVESTORS SERVICES, LLC 0.00% of their portfolio | 39.3k $152.0k | Reduced -39.3k |
| ExodusPoint Capital Management, LP 0.00% of their portfolio | 39.3k $152.0k | Reduced -1.7k |
| Jefferies Financial Group Inc. 0.00% of their portfolio | 35.0k $135.4k | Added +10.0k |
| Baader Bank Aktiengesellschaft 0.01% of their portfolio | 34.3k $82.0k | New |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 34.2k $133.0k | Added +2.8k |
| KRAEMATON INVESTMENT ADVISORS, INC 0.12% of their portfolio | 33.6k $130.0k | Reduced -1.5k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 32.9k $127.4k | Added +10.7k |
| WEALTH EFFECTS LLC 0.05% of their portfolio | 31.8k $122.9k | Added +900 |
| Verition Fund Management LLC 0.00% of their portfolio | 31.2k $120.6k | New |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 27.9k $108.1k | Added +2.7k |
| FARALLON CAPITAL MANAGEMENT, L.L.C. 0.00% of their portfolio | 27.6k $106.8k | Unchanged |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 26.0k $100.5k | Added +11.3k |
| Concurrent Investment Advisors, LLC 0.00% of their portfolio | 25.3k $97.7k | Added +3.6k |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC 0.00% of their portfolio | 24.8k $118.2k | Added +10.3k |
| OneDigital Investment Advisors LLC 0.00% of their portfolio | 24.1k $93.4k | Added +2.6k |
| DLD Asset Management, LP 0.01% of their portfolio | 22.6k $87.5k | New |
| MARSHALL WACE, LLP 0.00% of their portfolio | 22.1k $85.5k | Reduced -1.1m |
| PROFUND ADVISORS LLC 0.00% of their portfolio | 21.7k $84.0k | Reduced -8.0k |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 21.4k $83.0k | Unchanged |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 20.8k $80.6k | Reduced -17.1k |
| Glenmede Investment Management, LP 0.00% of their portfolio | 20.5k $79.2k | First filing |
| DEBUSSY CAPITAL MANAGEMENT LP 0.01% of their portfolio | 20.0k $77.4k | Unchanged |
| AlphaQuest LLC 0.01% of their portfolio | 19.8k $76.7k | Unchanged |
| ProShare Advisors LLC 0.00% of their portfolio | 18.9k $73.1k | Added +50 |
| Cambridge Investment Research Advisors, Inc. 0.00% of their portfolio | 18.7k $72.0k | Added +3.0k |
| Headlands Technologies LLC 0.01% of their portfolio | 18.6k $71.8k | New |
| SEI INVESTMENTS CO 0.00% of their portfolio | 18.4k $71.3k | New |
| B. Riley Wealth Advisors, Inc. 0.00% of their portfolio | 18.3k $70.8k | Reduced -6.0k |
| Cetera Investment Advisers 0.00% of their portfolio | 18.1k $70.2k | Reduced -4.7k |
| TWO SIGMA SECURITIES, LLC 0.01% of their portfolio | 18.1k $70.1k | New |