Altimmune, Inc.
US ˙ NasdaqGM ˙ US02155H2004

SecurityALT / Altimmune, Inc.
InstitutionNorthern Trust Corp
Latest Disclosed Ownership996,721 shares
Latest Disclosed Value $ 3,069,900
Northern Trust Corp reports 39.21% increase in ownership of ALT / Altimmune, Inc.

On May 14, 2026 - Northern Trust Corp filed a 13F-HR form disclosing ownership of 996,721 shares of Altimmune, Inc. (US:ALT) valued at $3,069,901 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 715,991 shares of Altimmune, Inc.. This represents a change in shares of 39.21% during the quarter. The current value of the position is $2,701,114 USD.

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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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)
2026-05-14 2026-03-31 13F ALTIMMUNE COM NEW 02155H200 996,721 280,730 39.21 3,070 18.77 0.0001
2026-02-17 2025-12-31 13F ALTIMMUNE COM NEW 02155H200 715,991 58,975 8.98 2,585 4.36 0.0003
2025-11-14 2025-09-30 13F ALTIMMUNE COM NEW 02155H200 657,016 16,670 2.60 2,477 -0.08 0.0003
2025-08-13 2025-06-30 13F ALTIMMUNE COM NEW 02155H200 640,346 3,640 0.57 2,478 -22.15 0.0003
2025-05-13 2025-03-31 13F ALTIMMUNE COM NEW 02155H200 636,706 -29,210 -4.39 3,184 -33.70 0.0005
2025-02-14 2024-12-31 13F ALTIMMUNE COM NEW 02155H200 665,916 35,918 5.70 4,801 24.12 0.0007
2024-11-13 2024-09-30 13F ALTIMMUNE COM 02155H200 629,998 102,701 19.48 3,868 10.33 0.0006
2024-08-14 2024-06-30 13F ALTIMMUNE COM 02155H200 527,297 33,329 6.75 3,507 -30.27 0.0006
2024-05-14 2024-03-31 13F ALTIMMUNE COM 02155H200 493,968 20,139 4.25 5,029 -5.67 0.0009
2024-02-13 2023-12-31 13F ALTIMMUNE COM 02155H200 473,829 23,419 5.20 5,331 355.17 0.0010
2023-11-13 2023-09-30 13F ALTIMMUNE COM 02155H200 450,410 27,974 6.62 1,171 -21.46 0.0002
2023-08-11 2023-06-30 13F ALTIMMUNE COM 02155H200 422,436 280,397 197.41 1,491 148.91 0.0003
2023-05-15 2023-03-31 13F ALTIMMUNE COM 02155H200 142,039 2,121 1.52 599 -73.97 0.0001
2023-02-13 2022-12-31 13F ALTIMMUNE COM 02155H200 139,918 28,529 25.61 2,302 61.81 0.0005
2022-11-14 2022-09-30 13F ALTIMMUNE COM 02155H200 111,389 9,600 9.43 1,422 19.40 0.0003
2022-08-12 2022-06-30 13F ALTIMMUNE COM 02155H200 101,789 -258,338 -71.74 1,191 -45.69 0.0003
2022-05-13 2022-03-31 13F ALTIMMUNE COM 02155H200 360,127 -16,357 -4.34 2,193 -36.42 0.0004
2022-02-08 2021-12-31 13F ALTIMMUNE COM 02155H200 376,484 -10,806 -2.79 3,449 -21.27 0.0006
2021-11-15 2021-09-30 13F ALTIMMUNE COM 02155H200 387,290 55,000 16.55 4,381 33.81 0.0008
2021-08-13 2021-06-30 13F ALTIMMUNE COM NEW 02155H200 332,290 241,637 266.55 3,274 155.58 0.0006
2021-05-12 2021-03-31 13F ALTIMMUNE COM 02155H200 90,653 -14,143 -13.50 1,281 8.38 0.0002
2021-02-11 2020-12-31 13F ALTIMMUNE COM 02155H200 104,796 -9,850 -8.59 1,182 -21.88 0.0002
2020-11-16 2020-09-30 13F ALTIMMUNE COM 02155H200 114,646 16,857 17.24 1,513 44.37 0.0003
2020-08-14 2020-06-30 13F ALTIMMUNE COM 02155H200 97,789 84,796 652.63 1,048 2,395.24 0.0002
2020-05-14 2020-03-31 13F ALTIMMUNE COM 02155H200 12,993 0 0.00 42 68.00 0.0000
2020-02-14 2019-12-31 13F ALTIMMUNE COM 02155H200 12,993 -2,863 -18.06 25 -19.35 0.0000
2019-11-13 2019-09-30 13F ALTIMMUNE COM 02155H200 15,856 -648,265 -97.61 31 -94.25 0.0000
2017-05-12 2017-03-31 13F PHARMATHENE COM 71714G102 664,121 4,619 0.70 539 -74.86 0.0002
2017-02-13 2016-12-31 13F PHARMATHENE COM 71714G102 659,502 4,691 0.72 2,144 12.90 0.0007
2016-11-09 2016-09-30 13F PHARMATHENE COM 71714G102 654,811 26,071 4.15 1,899 23.79 0.0006
2016-08-12 2016-06-30 13F PHARMATHENE COM 71714G102 628,740 565,992 902.01 1,534 1,189.08 0.0005
2016-08-19 2016-03-31 13F/A-1 PHARMATHENE COM 71714G102 62,748 -5,683 -8.30 119 -8.46 0.0000
2016-05-13 2016-03-31 13F PHARMATHENE COM 71714G102 62,748 119
2016-02-12 2015-12-31 13F PHARMATHENE COM 71714G102 68,431 0 0.00 130 42.86 0.0000
2015-11-12 2015-09-30 13F PHARMATHENE COM 71714G102 68,431 68,431 0.00 91 0.0000
2015-08-13 2015-06-30 13F PHARMATHENE COM 71714G102 0 -76,580 -100.00 0 -100.00
2015-05-14 2015-03-31 13F PHARMATHENE COM 71714G102 76,580 0 0.00 125 -10.07 0.0000
2015-02-12 2014-12-31 13F PHARMATHENE COM 71714G102 76,580 0 0.00 139 2.21 0.0000
2014-11-13 2014-09-30 13F PHARMATHENE COM 71714G102 76,580 -3,614 -4.51 136 20.35 0.0000
2014-08-14 2014-06-30 13F PHARMATHENE COM 71714G102 80,194 560 0.70 113 -22.60 0.0000
2014-05-14 2014-03-31 13F PHARMATHENE COM 71714G102 79,634 0 0.00 146 -1.35 0.0000
2014-02-21 2013-12-31 13F/A-1 PHARMATHENE COM 71714G102 79,634 -2,370 -2.89 148 -13.95 0.0000
2014-02-12 2013-12-31 13F PHARMATHENE COM 71714G102 79,634 148
2013-11-13 2013-09-30 13F PHARMATHENE COM 71714G102 82,004 1,865 2.33 172 34.38 0.0001
2013-08-09 2013-06-30 13F PHARMATHENE COM 71714G102 80,139 80,139 128 0.0000
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.