Altimmune, Inc.
US ˙ NasdaqGM ˙ US02155H2004

SecurityALT / Altimmune, Inc.
InstitutionDimensional Fund Advisors Lp
Latest Disclosed Ownership1,045,926 shares
Latest Disclosed Value $ 3,220,757
Dimensional Fund Advisors Lp reports 268.67% increase in ownership of ALT / Altimmune, Inc.

On May 7, 2026 - Dimensional Fund Advisors Lp filed a 13F-HR form disclosing ownership of 1,045,926 shares of Altimmune, Inc. (US:ALT) valued at $3,221,452 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 283,703 shares of Altimmune, Inc.. This represents a change in shares of 268.67% during the quarter. The current value of the position is $2,834,459 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.

Upgrade to unlock premium data and export to Excel .

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)
2026-05-07 2026-03-31 13F ALTIMMUNE COM NEW 02155H200 1,045,926 762,223 268.67 3,221 214.45 0.0007
2026-02-12 2025-12-31 13F ALTIMMUNE COM NEW 02155H200 283,703 -14,086 -4.73 1,024 -8.73 0.0002
2025-11-12 2025-09-30 13F ALTIMMUNE COM NEW 02155H200 297,789 -149,681 -33.45 1,123 -35.14 0.0002
2025-08-12 2025-06-30 13F ALTIMMUNE COM NEW 02155H200 447,470 -44,999 -9.14 1,730 -29.76 0.0004
2025-05-13 2025-03-31 13F ALTIMMUNE COM NEW 02155H200 492,469 -140,972 -22.25 2,463 -46.07 0.0006
2025-02-13 2024-12-31 13F ALTIMMUNE COM NEW 02155H200 633,441 -12,936 -2.00 4,567 15.07 0.0011
2024-11-07 2024-09-30 13F ALTIMMUNE COM NEW 02155H200 646,377 76,203 13.36 3,970 4.72 0.0010
2024-08-09 2024-06-30 13F ALTIMMUNE COM NEW 02155H200 570,174 335,444 142.91 3,791 58.64 0.0010
2024-05-10 2024-03-31 13F ALTIMMUNE COM NEW 02155H200 234,730 -26,788 -10.24 2,390 -18.80 0.0006
2024-02-07 2023-12-31 13F ALTIMMUNE COM NEW 02155H200 261,518 72,267 38.19 2,942 499.19 0.0009
2023-11-09 2023-09-30 13F ALTIMMUNE COM NEW 02155H200 189,251 -67,003 -26.15 492 -45.69 0.0002
2023-08-09 2023-06-30 13F ALTIMMUNE COM NEW 02155H200 256,254 -310,247 -54.77 905 -62.18 0.0003
2023-05-12 2023-03-31 13F ALTIMMUNE COM NEW 02155H200 566,501 388,636 218.50 2,391 119,400.00 0.0008
2023-02-09 2022-12-31 13F ALTIMMUNE COM NEW 02155H200 177,865 3,492 2.00 3 -99.91 0.0009
2022-11-10 2022-09-30 13F ALTIMMUNE COM NEW 02155H200 174,373 51,009 41.35 2,227 54.33 0.0009
2022-08-12 2022-06-30 13F ALTIMMUNE COM NEW 02155H200 123,364 50,662 69.68 1,443 225.73 0.0005
2022-05-13 2022-03-31 13F ALTIMMUNE COM 02155H200 72,702 -5,768 -7.35 443 -38.39 0.0001
2022-02-09 2021-12-31 13F ALTIMMUNE COM 02155H200 78,470 78,470 719 0.0002
2021-03-08 2020-12-31 13F/A-2 ALTIMMUNE COM 02155H200 0 -48,352 -100.00 0 -100.00
2020-11-12 2020-09-30 13F ALTIMMUNE COM 02155H200 48,352 0 0.00 638 23.17 0.0003
2020-08-13 2020-06-30 13F ALTIMMUNE COM 02155H200 48,352 0 0.00 518 234.19 0.0002
2020-05-14 2020-03-31 13F ALTIMMUNE COM 02155H200 48,352 -5,553 -10.30 155 51.96 0.0001
2020-02-14 2019-12-31 13F ALTIMMUNE COM 02155H200 53,905 -12,059 -18.28 102 -20.93 0.0000
2019-11-12 2019-09-30 13F ALTIMMUNE COM 02155H200 65,964 -8,648 -11.59 129 -27.53 0.0001
2019-08-13 2019-06-30 13F ALTIMMUNE COM 02155H200 74,612 0 0.00 178 -17.59 0.0001
2019-08-12 2019-03-31 13F/A-2 ALTIMMUNE COM 02155H200 74,612 12,706 20.52 216 68.75 0.0001
2019-05-10 2019-03-31 13F ALTIMMUNE COM 02155H200 74,612 12,706 216
2019-02-26 2018-12-31 13F/A-1 ALTIMMUNE COM 02155H200 61,906 -26,272 -29.79 128 77.78 0.0001
2019-02-13 2018-12-31 13F ALTIMMUNE COM 02155H200 61,906 -26,272 128
2017-05-12 2017-03-31 13F PHARMATHENE COM 71714G102 88,178 -96,222 -52.18 72 -87.98 0.0000
2017-02-09 2016-12-31 13F PHARMATHENE COM 71714G102 184,400 184,400 599 0.0003
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.