Altimmune, Inc.
Altimmune, Inc. (ALT) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · ALT · as of Sep 30, 2025
Ownership Breakdown
181
Institutional Holders
▼ 30 vs Q2
$156.56M
Total Inst. Value
▲ $11.04M vs Q2
88.26M
Shares Outstanding
freeFloat 99.21%
41.49M
13F Shares Held
▲ 3.88M vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
ALT largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
VANGUARD GROUP INC pharmaceutical preparations | 6.37M | 7.82% | 7.82% | $24.03B | Nov 7, 2025 | ▲ 1.21M |
BLACKROCK, INC. pharmaceutical preparations | 6.37M | 7.82% | 7.82% | $24.03B | Nov 12, 2025 | ▲ 699 |
STATE STREET CORP pharmaceutical preparations | 3.60M | 4.42% | 4.42% | $13.58B | Nov 14, 2025 | ▲ 847.6K |
TANG CAPITAL MANAGEMENT LLC pharmaceutical preparations | 2.13M | 2.62% | 2.62% | $8.04B | Nov 14, 2025 | ▼ 618.7K |
GEODE CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 2.02M | 2.48% | 2.48% | $7.61B | Nov 12, 2025 | ▲ 82.5K |
TWO SIGMA INVESTMENTS, LP pharmaceutical preparations | 2.00M | 2.45% | 2.45% | $7.53B | Nov 14, 2025 | ▲ 1.56M |
SUSQUEHANNA INTERNATIONAL GROUP, LLP pharmaceutical preparations | 1.69M | 2.07% | 2.07% | $6.36B | Nov 14, 2025 | ▲ 826.8K |
MORGAN STANLEY pharmaceutical preparations | 1.49M | 1.83% | 1.83% | $5.62B | May 27, 2026 | ▲ 655.6K |
TWO SIGMA ADVISERS, LP pharmaceutical preparations | 1.43M | 1.75% | 1.75% | $5.39B | Nov 14, 2025 | ▲ 1.30M |
SUSQUEHANNA INTERNATIONAL GROUP, LLP pharmaceutical preparations | 1.37M | 1.69% | 1.69% | $5.18B | Nov 14, 2025 | ▼ 245.6K |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
34
Increased
+10.19M shares2
New Positions
first time holders12
Decreased
−3.42M shares0
Sold Out
fully exitedNet shares change (top 50)
+6.77M
+10.19M / −3.42M
Net new holders
+24
2 new / 0 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
ALT insider trading · insider activity
Source: SEC Form 4
Insiders have been net buyers of shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
11
Buy transactions
0
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
Lawver Teri L director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
Sohn Catherine A. director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
Jorkasky Diane director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
Schafer Klaus director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
Pisano Wayne director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
Hodges Philip director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
GILL JOHN director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
SAYARE MITCHEL director | May 1, 2026 | Award | 48,800 | $2.82 | $137.6K | 48.8K | Form 4 ↗ |
GILL JOHN director | Apr 6, 2026 | Purchase | 9,200 | $3.41 | $31.3K | 21.7K | Form 4 ↗ |
WEAVER GREGORY L Chief Financial Officer | Apr 1, 2026 | Purchase | 10,000 | $3.15 | $31.5K | 38.1K | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
Altimmune, Inc. (ALT) is primarily owned by institutional investors, who hold approximately 47.0% of total shares outstanding. Company insiders own approximately 0.79%, while retail and public investors account for the remaining 52.20%.
The largest institutional shareholder of Altimmune, Inc. is VANGUARD GROUP INC, holding approximately 6.37 million shares — equal to 7.82% of outstanding shares — as of September 30, 2025.
A total of 181 institutional investors currently hold ALT stock, with a combined institutional value of approximately $156,558,878 as of the most recent 13F filing period.
Frequently asked questions
ALT ownershipAltimmune, Inc. (ALT) is primarily owned by institutional investors, who hold approximately 47.0% of shares. The largest shareholder is VANGUARD GROUP INC with a 7.82% stake. Company insiders hold 0.79%. Data sourced from SEC Form 13F as of September 30, 2025.