Altimmune, Inc.
US ˙ NasdaqGM ˙ US02155H2004

SecurityALT / Altimmune, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership448,873 shares
Latest Disclosed Value $ 1,382,528
Citadel Advisors Llc ownership in ALT / Altimmune, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 448,873 shares of Altimmune, Inc. (US:ALT) valued at $1,382,529 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 1,337,927 shares of Altimmune, Inc.. This represents a change in shares of -66.45% during the quarter. The current value of the position is $1,288,266 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (ALT) in the form of stock options. The firm currently holds call options representing 337,900 of underlying shares valued at $1,040,732 USD and put options representing 195,600 of underlying shares valued at $602,448 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

ALT / Altimmune, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F ALTIMMUNE COM NEW 02155H200 448,873 -889,054 -66.45 1,383 -71.38 0.0002
2026-02-17 2025-12-31 13F ALTIMMUNE COM NEW 02155H200 1,337,927 55,913 4.36 4,830 -0.08 0.0007
2025-11-14 2025-09-30 13F ALTIMMUNE COM NEW 02155H200 1,282,014 758,553 144.91 4,833 138.67 0.0007
2025-08-14 2025-06-30 13F ALTIMMUNE COM NEW 02155H200 523,461 523,461 2,026 0.0004
2025-05-15 2025-03-31 13F ALTIMMUNE COM NEW 02155H200 0 -675,044 -100.00 0 -100.00
2025-02-14 2024-12-31 13F ALTIMMUNE COM NEW 02155H200 675,044 247,457 57.87 4,867 85.41 0.0008
2024-11-14 2024-09-30 13F ALTIMMUNE COM NEW 02155H200 427,587 426,566 41,779.24 2,625 43,650.00 0.0005
2024-08-14 2024-06-30 13F ALTIMMUNE COM NEW 02155H200 1,021 -75,046 -98.66 7 -99.22 0.0000
2024-05-15 2024-03-31 13F ALTIMMUNE COM NEW 02155H200 76,067 76,067 774 0.0001
2024-02-14 2023-12-31 13F ALTIMMUNE COM NEW 02155H200 0 -119,404 -100.00 0 -100.00
2023-11-14 2023-09-30 13F ALTIMMUNE COM NEW 02155H200 119,404 -211,425 -63.91 310 -73.44 0.0001
2023-08-14 2023-06-30 13F ALTIMMUNE COM NEW 02155H200 330,829 -1,713,656 -83.82 1,168 -86.47 0.0002
2023-05-15 2023-03-31 13F ALTIMMUNE COM NEW 02155H200 2,044,485 885,024 76.33 8,628 -54.77 0.0019
2023-02-14 2022-12-31 13F ALTIMMUNE COM NEW 02155H200 1,159,461 1,030,210 797.06 19,073 1,055.24 0.0045
2022-11-14 2022-09-30 13F ALTIMMUNE COM NEW 02155H200 129,251 -1,018,607 -88.74 1,651 -87.71 0.0004
2022-08-15 2022-06-30 13F ALTIMMUNE COM NEW 02155H200 1,147,858 23,451 2.09 13,430 96.12 0.0034
2022-05-16 2022-03-31 13F ALTIMMUNE COM NEW 02155H200 1,124,407 86,453 8.33 6,848 -27.98 0.0014
2022-02-14 2021-12-31 13F ALTIMMUNE COM NEW 02155H200 1,037,954 -51,898 -4.76 9,508 -22.86 0.0019
2021-11-15 2021-09-30 13F ALTIMMUNE Cmn 02155H200 1,089,852 -201,013 -15.57 12,326 -3.06 0.0026
2021-08-16 2021-06-30 13F ALTIMMUNE COM NEW 02155H200 1,290,865 160,606 14.21 12,715 -20.38 0.0028
2021-05-21 2021-03-31 13F/A-1 ALTIMMUNE COM NEW 02155H200 1,130,259 20,415 1.84 15,970 27.57 0.0039
2021-05-17 2021-03-31 13F ALTIMMUNE COM NEW 02155H200 1,130,259 20,415 15,970 0.0039
2021-02-16 2020-12-31 13F ALTIMMUNE COM NEW 02155H200 1,109,844 664,907 149.44 12,519 113.16 0.0033
2020-11-16 2020-09-30 13F ALTIMMUNE COM NEW 02155H200 444,937 -123,960 -21.79 5,873 -3.61 0.0017
2020-08-14 2020-06-30 13F ALTIMMUNE Cmn 02155H200 568,897 568,897 27.86 6,093 3.75 0.0022
2020-05-15 2020-03-31 13F ALTIMMUNE Cmn 02155H200 0 -24,319 -100.00 0 -100.00
2020-02-14 2019-12-31 13F ALTIMMUNE Cmn 02155H200 24,319 7,295 42.85 46 39.39 0.0000
2019-11-14 2019-09-30 13F ALTIMMUNE Cmn 02155H200 17,024 -7,790 -31.39 33 -44.07 0.0000
2019-08-14 2019-06-30 13F ALTIMMUNE Cmn 02155H200 24,814 11,733 89.69 59 55.26 0.0000
2019-05-15 2019-03-31 13F ALTIMMUNE Cmn 02155H200 13,081 -258,066 -95.18 38 -82.73 0.0000
2017-05-12 2017-03-31 13F PHARMATHENE Cmn 71714G102 271,147 271,147 443.12 220 900.00 0.0002
2017-02-10 2016-12-31 13F PHARMATHENE Cmn 71714G102 0 -12,638 -100.00 0 -100.00
2017-01-31 2016-09-30 13F/A-1 PHARMATHENE Cmn 71714G102 12,638 -37,096 -74.59 37 -69.42 0.0000
2016-11-10 2016-09-30 13F PHARMATHENE Cmn 71714G102 12,638 37
2017-01-31 2016-06-30 13F/A-1 PHARMATHENE Cmn 71714G102 49,734 6,737 15.67 121 49.38 0.0001
2016-08-12 2016-06-30 13F PHARMATHENE Cmn 71714G102 49,734 121
2017-01-31 2016-03-31 13F/A-1 PHARMATHENE Cmn 71714G102 42,997 42,997 -13.55 81 -33.06 0.0001
2016-05-13 2016-03-31 13F PHARMATHENE Cmn 71714G102 42,997 81
2015-05-15 2015-03-31 13F PHARMATHENE Cmn 71714G102 0 -16,306 -100.00 0 -100.00
2015-02-17 2014-12-31 13F PHARMATHENE Cmn 71714G102 16,306 -319 -1.92 30 0.00 0.0000
2014-11-14 2014-09-30 13F PHARMATHENE Cmn 71714G102 16,625 11,458 221.75 30 328.57 0.0000
2014-08-14 2014-06-30 13F PHARMATHENE Cmn 71714G102 5,167 -26,742 -83.81 7 -87.93 0.0000
2014-05-15 2014-03-31 13F PHARMATHENE Cmn 71714G102 31,909 31,909 58 0.0001
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F ALTIMMUNE COM NEW Call 337,900 -20.16 1,041 -31.89 n/a n/a n/a
2026-02-17 2025-12-31 13F ALTIMMUNE COM NEW Call 423,200 14.47 1,528 9.62 n/a n/a n/a
2025-11-14 2025-09-30 13F ALTIMMUNE COM NEW Call 369,700 41.81 1,394 38.19 n/a n/a n/a
2025-08-14 2025-06-30 13F ALTIMMUNE COM NEW Call 260,700 -17.58 1,009 -36.24 n/a n/a n/a
2025-05-15 2025-03-31 13F ALTIMMUNE COM NEW Call 316,300 29.47 1,582 -10.22 n/a n/a n/a
2025-02-14 2024-12-31 13F ALTIMMUNE COM NEW Call 244,300 -20.09 1,761 -6.13 n/a n/a n/a
2024-11-14 2024-09-30 13F ALTIMMUNE COM NEW Call 305,700 14.80 1,877 5.99 n/a n/a n/a
2024-08-14 2024-06-30 13F ALTIMMUNE COM NEW Call 266,300 -15.65 1,771 -44.91 n/a n/a n/a
2024-05-15 2024-03-31 13F ALTIMMUNE COM NEW Call 315,700 29.07 3,214 16.79 n/a n/a n/a
2024-02-14 2023-12-31 13F ALTIMMUNE COM NEW Call 244,600 112.14 2,752 820.07 n/a n/a n/a
2023-11-14 2023-09-30 13F ALTIMMUNE COM NEW Call 115,300 11.40 300 -18.08 n/a n/a n/a
2023-08-14 2023-06-30 13F ALTIMMUNE COM NEW Call 103,500 -62.25 365 -68.45 n/a n/a n/a
2023-05-15 2023-03-31 13F ALTIMMUNE COM NEW Call 274,200 52.00 1,157 -61.00 n/a n/a n/a
2023-02-14 2022-12-31 13F ALTIMMUNE COM NEW Call 180,400 -35.94 2,968 -17.49 n/a n/a n/a
2022-11-14 2022-09-30 13F ALTIMMUNE COM NEW Call 281,600 58.56 3,596 73.05 n/a n/a n/a
2022-08-15 2022-06-30 13F ALTIMMUNE COM NEW Call 177,600 47.88 2,078 184.27 n/a n/a n/a
2022-05-16 2022-03-31 13F ALTIMMUNE COM NEW Call 120,100 0.59 731 -33.18 n/a n/a n/a
2022-02-14 2021-12-31 13F ALTIMMUNE COM NEW Call 119,400 -34.40 1,094 -46.84 n/a n/a n/a
2021-11-15 2021-09-30 13F ALTIMMUNE Cmn Call 182,000 199.34 2,058 243.57 n/a n/a n/a
2021-08-16 2021-06-30 13F ALTIMMUNE COM NEW Call 60,800 -43.65 599 -60.72 n/a n/a n/a
2021-05-21 2021-03-31 13F/A ALTIMMUNE COM NEW Call 107,900 12.75 1,525 41.20 n/a n/a n/a
2021-05-17 2021-03-31 13F ALTIMMUNE COM NEW Call 107,900 1,525 n/a n/a n/a
2021-02-16 2020-12-31 13F ALTIMMUNE COM NEW Call 95,700 42.84 1,080 22.17 n/a n/a n/a
2020-11-16 2020-09-30 13F ALTIMMUNE COM NEW Call 67,000 -76.65 884 -71.23 n/a n/a n/a
2020-08-14 2020-06-30 13F ALTIMMUNE Cmn Call 286,900 412.32 3,073 1,607.22 n/a n/a n/a
2020-05-15 2020-03-31 13F ALTIMMUNE Cmn Call 56,000 164.15 180 350.00 n/a n/a n/a
2020-02-14 2019-12-31 13F ALTIMMUNE Cmn Call 21,200 7.07 40 2.56 n/a n/a n/a
2019-11-14 2019-09-30 13F ALTIMMUNE Cmn Call 19,800 20.00 39 0.00 n/a n/a n/a
2019-08-14 2019-06-30 13F ALTIMMUNE Cmn Call 16,500 -75.08 39 -79.69 n/a n/a n/a
2019-05-15 2019-03-31 13F ALTIMMUNE Cmn Call 66,200 376.26 192 562.07 n/a n/a n/a
2019-02-14 2018-12-31 13F ALTIMMUNE Cmn Call 13,900 -79.00 29 -84.90 n/a n/a n/a
2017-05-12 2017-03-31 13F PHARMATHENE Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2017-02-10 2016-12-31 13F PHARMATHENE Cmn Call 44,300 144 n/a n/a n/a
2015-05-15 2015-03-31 13F PHARMATHENE Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2015-02-17 2014-12-31 13F PHARMATHENE Cmn Call 200 0 n/a n/a n/a
2014-11-14 2014-09-30 13F PHARMATHENE Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2014-08-14 2014-06-30 13F PHARMATHENE Cmn Call 3,500 52.17 5 25.00 n/a n/a n/a
2014-05-15 2014-03-31 13F PHARMATHENE Cmn Call 2,300 -87.08 4 -85.71 n/a n/a n/a
2013-08-14 2013-06-30 13F HEALTHCARE ACQUISITION Cmn Call 17,800 28 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F ALTIMMUNE COM NEW Put 195,600 -66.19 602 -71.17 n/a n/a n/a
2026-02-17 2025-12-31 13F ALTIMMUNE COM NEW Put 578,500 57.72 2,088 51.09 n/a n/a n/a
2025-11-14 2025-09-30 13F ALTIMMUNE COM NEW Put 366,800 -58.62 1,383 -59.71 n/a n/a n/a
2025-08-14 2025-06-30 13F ALTIMMUNE COM NEW Put 886,400 251.19 3,430 171.79 n/a n/a n/a
2025-05-15 2025-03-31 13F ALTIMMUNE COM NEW Put 252,400 -30.04 1,262 -51.48 n/a n/a n/a
2025-02-14 2024-12-31 13F ALTIMMUNE COM NEW Put 360,800 67.04 2,601 96.15 n/a n/a n/a
2024-11-14 2024-09-30 13F ALTIMMUNE COM NEW Put 216,000 47.24 1,326 36.00 n/a n/a n/a
2024-08-14 2024-06-30 13F ALTIMMUNE COM NEW Put 146,700 -41.16 976 -61.57 n/a n/a n/a
2024-05-15 2024-03-31 13F ALTIMMUNE COM NEW Put 249,300 -12.03 2,538 -20.42 n/a n/a n/a
2024-02-14 2023-12-31 13F ALTIMMUNE COM NEW Put 283,400 138.55 3,188 935.06 n/a n/a n/a
2023-11-14 2023-09-30 13F ALTIMMUNE COM NEW Put 118,800 40.43 309 3.36 n/a n/a n/a
2023-08-14 2023-06-30 13F ALTIMMUNE COM NEW Put 84,600 -68.26 299 -73.49 n/a n/a n/a
2023-05-15 2023-03-31 13F ALTIMMUNE COM NEW Put 266,500 182.31 1,125 -27.58 n/a n/a n/a
2023-02-14 2022-12-31 13F ALTIMMUNE COM NEW Put 94,400 -61.94 1,553 -50.99 n/a n/a n/a
2022-11-14 2022-09-30 13F ALTIMMUNE COM NEW Put 248,000 788.89 3,167 871.47 n/a n/a n/a
2022-08-15 2022-06-30 13F ALTIMMUNE COM NEW Put 27,900 -13.08 326 67.18 n/a n/a n/a
2022-05-16 2022-03-31 13F ALTIMMUNE COM NEW Put 32,100 -51.73 195 -67.98 n/a n/a n/a
2022-02-14 2021-12-31 13F ALTIMMUNE COM NEW Put 66,500 -63.76 609 -70.65 n/a n/a n/a
2021-11-15 2021-09-30 13F ALTIMMUNE Cmn Put 183,500 -33.71 2,075 -23.88 n/a n/a n/a
2021-08-16 2021-06-30 13F ALTIMMUNE COM NEW Put 276,800 167.18 2,726 86.20 n/a n/a n/a
2021-05-21 2021-03-31 13F/A ALTIMMUNE COM NEW Put 103,600 -9.83 1,464 12.96 n/a n/a n/a
2021-05-17 2021-03-31 13F ALTIMMUNE COM NEW Put 103,600 1,464 n/a n/a n/a
2021-02-16 2020-12-31 13F ALTIMMUNE COM NEW Put 114,900 34.70 1,296 15.10 n/a n/a n/a
2020-11-16 2020-09-30 13F ALTIMMUNE COM NEW Put 85,300 147.25 1,126 205.15 n/a n/a n/a
2020-08-14 2020-06-30 13F ALTIMMUNE Cmn Put 34,500 155.56 369 758.14 n/a n/a n/a
2020-05-15 2020-03-31 13F ALTIMMUNE Cmn Put 13,500 -60.87 43 -88.35 n/a n/a n/a
2019-08-14 2019-06-30 13F ALTIMMUNE Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2019-05-15 2019-03-31 13F ALTIMMUNE Cmn Put 15,200 44 n/a n/a n/a
2016-11-10 2016-09-30 13F PHARMATHENE Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2017-01-31 2016-06-30 13F/A PHARMATHENE Cmn Put 12,100 -45.74 30 -28.57 n/a n/a n/a
2016-08-12 2016-06-30 13F PHARMATHENE Cmn Put 12,100 30 n/a n/a n/a
2017-01-31 2016-03-31 13F/A PHARMATHENE Cmn Put 22,300 84.30 42 40.00 n/a n/a n/a
2016-05-13 2016-03-31 13F PHARMATHENE Cmn Put 22,300 42 n/a n/a n/a
2015-05-15 2015-03-31 13F PHARMATHENE Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2015-02-17 2014-12-31 13F PHARMATHENE Cmn Put 7,600 -44.53 14 -41.67 n/a n/a n/a
2014-11-14 2014-09-30 13F PHARMATHENE Cmn Put 13,700 110.77 24 166.67 n/a n/a n/a
2014-08-14 2014-06-30 13F PHARMATHENE Cmn Put 6,500 364.29 9 200.00 n/a n/a n/a
2014-05-15 2014-03-31 13F PHARMATHENE Cmn Put 1,400 -36.36 3 0.00 n/a n/a n/a
2013-08-14 2013-06-30 13F HEALTHCARE ACQUISITION Cmn Put 2,200 3 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.