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 ($20.7k this quarter). Holder counts are more reliable. Shares outstanding: 130.1m as of 2026-02-27, 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 ≈ $3.61. Options: 15 managers hold calls ($13.4m notional), 12 hold puts ($15.7m).
Trends to Q4 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 |
| Q3 2025 | 158 |
| Q4 2025 | 184 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q1 2024 | 108 | 68 |
| Q2 2024 | 95 | 86 |
| Q3 2024 | 79 | 71 |
| Q4 2024 | 90 | 68 |
| Q1 2025 | 80 | 78 |
| Q2 2025 | 108 | 75 |
| Q3 2025 | 79 | 89 |
| Q4 2025 | 117 | 50 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q1 2025 | $13.5m | $10.3m | 0.76 |
| Q2 2025 | $26.3m | $22.6m | 0.86 |
| Q3 2025 | $19.2m | $14.1m | 0.73 |
| Q4 2025 | $13.4m | $15.7m | 1.18 |
Biggest buyers
| BlackRock, Inc. | Added | +3.3m |
| VANGUARD GROUP INC | Added | +3.1m |
| STATE STREET CORP | Added | +1.5m |
| JANE STREET GROUP, LLC | Added | +1.5m |
| Nuveen, LLC | Added | +1.0m |
| D. E. Shaw & Co., Inc. | Added | +983.2k |
| MARSHALL WACE, LLP | New | +922.8k |
| GOLDMAN SACHS GROUP INC | Added | +787.0k |
| SCHRODER INVESTMENT MANAGEMENT GROUP | New | +469.0k |
| Soviero Asset Management, LP | New | +400.0k |
Biggest sellers
| TWO SIGMA INVESTMENTS, LP | Reduced | -731.2k |
| TWO SIGMA ADVISERS, LP | Reduced | -634.5k |
| Squarepoint Ops LLC | Reduced | -549.7k |
| Point72 Asset Management, L.P. | Sold out | -476.9k |
| SIMPLEX TRADING, LLC | Sold out | -213.7k |
| ExodusPoint Capital Management, LP | Reduced | -166.3k |
| MILLENNIUM MANAGEMENT LLC | Reduced | -160.2k |
| MORGAN STANLEY | Reduced | -131.2k |
| GSA CAPITAL PARTNERS LLP | Sold out | -116.8k |
| GROUP ONE TRADING LLC | Reduced | -108.9k |
Biggest calls
| GROUP ONE TRADING LLC | Added | $2.4m664.2k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $2.0m541.3k shares |
| DIADEMA PARTNERS LP | Added | $1.8m491.8k shares |
| CITADEL ADVISORS LLC | Added | $1.5m423.2k shares |
| SIMPLEX TRADING, LLC | Added | $1.4m376.8k shares |
| UBS Group AG | Reduced | $994.6k275.5k shares |
| IMC-Chicago, LLC | Reduced | $989.5k274.1k shares |
| JANE STREET GROUP, LLC | Added | $576.9k159.8k shares |
| DCF Advisers, LLC | New | $570.4k158.0k shares |
| PEAK6 LLC | Reduced | $563.2k156.0k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $6.4m1.8m shares |
| CITADEL ADVISORS LLC | Added | $2.1m578.5k shares |
| SIMPLEX TRADING, LLC | Added | $2.0m562.6k shares |
| GROUP ONE TRADING LLC | Added | $1.5m423.7k shares |
| Sculptor Capital LP | Unchanged | $998.9k276.7k shares |
| IMC-Chicago, LLC | Added | $929.2k257.4k shares |
| LMR Partners LLP | Unchanged | $902.5k250.0k shares |
| JANE STREET GROUP, LLC | Added | $376.9k104.4k shares |
| Jefferies Financial Group Inc. | Unchanged | $180.5k50.0k shares |
| Verition Fund Management LLC | Unchanged | $180.5k50.0k 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 Q4 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 |
|---|---|---|---|---|---|
| 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 | — | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 3 | $104.9k | 0 | — | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2025-12-29 | Jorkasky Diane Director | Bought | $2.0k527 shares |
| 2025-12-23 | GILL JOHN Director | Bought | $51.2k12.5k shares |
| 2025-12-22 | Durso Jerome Benedict Director | Bought | $51.6k12.5k 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, Q4 2025
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 9.7m $35.0m | Added +3.3m |
| VANGUARD GROUP INC 0.00% of their portfolio | 9.5m $34.3m | Added +3.1m |
| STATE STREET CORP 0.00% of their portfolio | 5.1m $18.5m | Added +1.5m |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 2.3m $8.3m | Added +275.0k |
| TANG CAPITAL MANAGEMENT LLC 0.38% of their portfolio | 2.1m $7.7m | Unchanged |
| JANE STREET GROUP, LLC 0.01% of their portfolio | 1.8m $6.4m | Added +1.5m |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.01% of their portfolio | 1.4m $4.9m | Reduced -5.2k |
| MORGAN STANLEY 0.00% of their portfolio | 1.4m $4.9m | Reduced -131.2k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 1.3m $4.9m | Added +787.0k |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 1.3m $4.9m | Added +983.2k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 1.3m $4.8m | Added +55.9k |
| TWO SIGMA INVESTMENTS, LP 0.01% of their portfolio | 1.3m $4.6m | Reduced -731.2k |
| Nuveen, LLC 0.00% of their portfolio | 1.2m $4.5m | Added +1.0m |
| Knoll Capital Management, LLC 1.86% of their portfolio | 1.1m $4.0m | Unchanged |
| MARSHALL WACE, LLP 0.00% of their portfolio | 922.8k $3.3m | New |
| TWO SIGMA ADVISERS, LP 0.01% of their portfolio | 793.9k $2.9m | Reduced -634.5k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 716.0k $2.6m | Added +59.0k |
| UBS Group AG 0.00% of their portfolio | 642.0k $2.3m | Reduced -789 |
| FMR LLC 0.00% of their portfolio | 564.1k $2.0m | Added +119.0k |
| SCHRODER INVESTMENT MANAGEMENT GROUP 0.00% of their portfolio | 469.0k $1.7m | New |
| BARCLAYS PLC 0.00% of their portfolio | 400.6k $1.4m | Added +60.3k |
| Soviero Asset Management, LP 0.75% of their portfolio | 400.0k $1.4m | New |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 383.8k $1.4m | Added +63.3k |
| Beirne Wealth Consulting Services, LLC 0.39% of their portfolio | 376.5k $1.4m | Reduced -34.0k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 354.2k $1.3m | Added +12.2k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 283.7k $1.0m | Reduced -14.1k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 283.7k $1.0m | Added +79.2k |
| Sculptor Capital LP 0.01% of their portfolio | 276.7k $998.9k | Unchanged |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 264.4k $948.0k | Added +191.3k |
| BROWN WEALTH MANAGEMENT, LLC 0.25% of their portfolio | 258.7k $933.8k | Added +25.0k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 257.3k $928.7k | Reduced -7.5k |
| Steward Partners Investment Advisory, LLC 0.00% of their portfolio | 245.4k $885.9k | Added +26.1k |
| Jump Financial, LLC 0.01% of their portfolio | 242.0k $873.7k | Added +126.2k |
| Pavaki Capital Management LLC 0.54% of their portfolio | 215.4k $777.6k | First filing |
| Invesco Ltd. 0.00% of their portfolio | 214.8k $775.5k | Added +52.9k |
| Hennion & Walsh Asset Management, Inc. 0.03% of their portfolio | 214.6k $774.8k | Added +29.1k |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 207.4k $748.7k | Reduced -160.2k |
| Rafferty Asset Management, LLC 0.00% of their portfolio | 195.8k $706.7k | Added +39.6k |
| COMMONWEALTH EQUITY SERVICES, LLC 0.00% of their portfolio | 181.5k $655.1k | Added +7.4k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 177.3k $640.1k | Added +102.8k |
| IMC-Chicago, LLC 0.01% of their portfolio | 173.1k $625.0k | Added +57.8k |
| Grantham, Mayo, Van Otterloo & Co. LLC 0.00% of their portfolio | 172.6k $622.9k | New |
| Jefferies Financial Group Inc. 0.00% of their portfolio | 157.8k $569.7k | Added +107.8k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 141.3k $510.0k | Added +48.4k |
| Susquehanna Portfolio Strategies, LLC 0.01% of their portfolio | 135.2k $488.0k | Reduced -50.1k |
| LOS ANGELES CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 128.5k $523.1k | New |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.00% of their portfolio | 124.8k $450.6k | New |
| STIFEL FINANCIAL CORP 0.00% of their portfolio | 123.4k $445.5k | Added +63.0k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 121.5k $438.7k | Reduced -9.2k |
| Baird Financial Group, Inc. 0.00% of their portfolio | 119.4k $431.2k | Unchanged |
| Brevan Howard Capital Management LP 0.01% of their portfolio | 114.1k $412.0k | Reduced -108.8k |
| WEALTH EFFECTS LLC 0.13% of their portfolio | 111.8k $403.4k | Added +51.9k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 104.5k $377.4k | Reduced -93.8k |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.00% of their portfolio | 103.5k $373.6k | Unchanged |
| Summit Financial Wealth Advisors, LLC 0.05% of their portfolio | 103.3k $372.9k | Added +7.0k |
| Janney Montgomery Scott LLC 0.00% of their portfolio | 102.6k $370.0k | Added +44.0k |
| NOMURA ASSET MANAGEMENT INTERNATIONAL INC. 0.00% of their portfolio | 100.0k $361.0k | First filing |
| Engineers Gate Manager LP 0.00% of their portfolio | 87.3k $315.0k | Added +46.2k |
| ALPS ADVISORS INC 0.00% of their portfolio | 85.7k $309.3k | New |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 79.9k $288.6k | Added +3.0k |
| Caption Management, LLC 0.01% of their portfolio | 74.4k $268.7k | Reduced -55.6k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 73.8k $266.6k | Reduced -474 |
| PROFUND ADVISORS LLC 0.01% of their portfolio | 72.3k $261.0k | Added +38.6k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 71.8k $259.1k | Unchanged |
| Verition Fund Management LLC 0.00% of their portfolio | 69.5k $250.8k | Added +38.3k |
| Walleye Capital LLC 0.00% of their portfolio | 65.7k $237.1k | Added +50.1k |
| LMR Partners LLP 0.00% of their portfolio | 61.3k $221.3k | New |
| Balyasny Asset Management L.P. 0.00% of their portfolio | 60.1k $217.0k | New |
| Virtu Financial LLC 0.01% of their portfolio | 58.5k $211.0k | Added +10.4k |
| BLAIR WILLIAM & CO/IL 0.00% of their portfolio | 56.4k $203.7k | New |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 55.9k $201.7k | Added +28.2k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 52.6k $189.8k | Added +6.7k |
| INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 52.6k $189.7k | Added +13.9k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 50.6k $182.7k | Unchanged |
| Virtus Investment Advisers, LLC 0.05% of their portfolio | 50.5k $182.2k | Added +34.6k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 49.9k $181.0k | Added +8.4k |
| LPL Financial LLC 0.00% of their portfolio | 48.6k $175.5k | Reduced -12.9k |
| Voleon Capital Management LP 0.00% of their portfolio | 47.1k $169.9k | New |
| Creative Planning 0.00% of their portfolio | 46.9k $169.3k | Added +10.5k |
| Rockefeller Capital Management L.P. 0.00% of their portfolio | 43.2k $155.8k | Added +43.1k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 38.2k $137.9k | Reduced -6.3k |
| KINGSWOOD WEALTH ADVISORS, LLC 0.01% of their portfolio | 36.0k $130.0k | Added +20.6k |
| ACADIAN ASSET MANAGEMENT LLC 0.00% of their portfolio | 35.7k $128.0k | New |
| Kovack Advisors, Inc. 0.01% of their portfolio | 35.2k $127.1k | New |
| Squarepoint Ops LLC 0.00% of their portfolio | 34.9k $126.2k | Reduced -549.7k |
| MML INVESTORS SERVICES, LLC 0.00% of their portfolio | 34.5k $124.7k | Unchanged |
| GROUP ONE TRADING LLC 0.00% of their portfolio | 31.4k $113.3k | Reduced -108.9k |
| FOX RUN MANAGEMENT, L.L.C. 0.02% of their portfolio | 30.6k $110.5k | New |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 30.0k $108.3k | New |
| Cetera Investment Advisers 0.00% of their portfolio | 29.7k $107.2k | Added +9.5k |
| CITIGROUP INC 0.00% of their portfolio | 28.3k $102.2k | Added +18.6k |
| FARALLON CAPITAL MANAGEMENT, L.L.C. 0.00% of their portfolio | 27.6k $99.6k | Unchanged |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 27.6k $99.6k | Added +1.6k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 27.4k $99.0k | Reduced -39.3k |
| Concurrent Investment Advisors, LLC 0.00% of their portfolio | 26.5k $95.7k | Added +2.5k |
| AXQ CAPITAL, LP 0.02% of their portfolio | 25.7k $92.8k | Added +5.3k |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 23.6k $85.1k | Unchanged |
| DRW Securities, LLC 0.01% of their portfolio | 22.5k $81.1k | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 21.4k $77.4k | Unchanged |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 21.1k $76.3k | New |