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 Mar 31, 2025
Ownership Breakdown
195
Institutional Holders
▼ 10 vs Q4
$191.10M
Total Inst. Value
▼ $100.74M vs Q4
88.26M
Shares Outstanding
freeFloat 99.21%
38.16M
13F Shares Held
▼ 2.32M vs Q4
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
Q1 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
BLACKROCK, INC. pharmaceutical preparations | 6.14M | 8.12% | 8.12% | $30.68B | May 2, 2025 | ▼ 24.1K |
VANGUARD GROUP INC pharmaceutical preparations | 4.41M | 5.83% | 5.83% | $22.04B | May 9, 2025 | ▼ 24.1K |
STATE STREET CORP pharmaceutical preparations | 3.39M | 4.49% | 4.49% | $16.96B | May 15, 2025 | ▼ 78.4K |
TANG CAPITAL MANAGEMENT LLC pharmaceutical preparations | 2.75M | 3.64% | 3.64% | $13.75B | May 15, 2025 | — held |
GEODE CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 1.71M | 2.26% | 2.26% | $8.53B | May 13, 2025 | ▲ 47.4K |
AMERIPRISE FINANCIAL INC pharmaceutical preparations | 1.44M | 1.91% | 1.91% | $7.22B | May 14, 2025 | ▼ 3.81M |
MARSHALL WACE, LLP pharmaceutical preparations | 1.17M | 1.55% | 1.55% | $5.84B | May 15, 2025 | ▲ 1.10M |
TWO SIGMA INVESTMENTS, LP pharmaceutical preparations | 1.15M | 1.52% | 1.52% | $5.74B | May 15, 2025 | ▲ 542.5K |
KNOLL CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 1.12M | 1.48% | 1.48% | $5.61B | May 15, 2025 | — held |
MILLENNIUM MANAGEMENT LLC pharmaceutical preparations | 1.11M | 1.47% | 1.47% | $5.56B | May 15, 2025 | ▲ 765.7K |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q1 2025 vs prior quarter
Q1 2025
25
Increased
+5.37M shares4
New Positions
first time holders15
Decreased
−5.35M shares0
Sold Out
fully exitedNet shares change (top 50)
+21.7K
+5.37M / −5.35M
Net new holders
+14
4 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 43.2% of total shares outstanding. Company insiders own approximately 0.79%, while retail and public investors account for the remaining 55.97%.
The largest institutional shareholder of Altimmune, Inc. is BLACKROCK, INC., holding approximately 6.14 million shares — equal to 8.12% of outstanding shares — as of March 31, 2025.
A total of 195 institutional investors currently hold ALT stock, with a combined institutional value of approximately $191,097,159 as of the most recent 13F filing period.
Frequently asked questions
ALT ownershipAltimmune, Inc. (ALT) is primarily owned by institutional investors, who hold approximately 43.2% of shares. The largest shareholder is BLACKROCK, INC. with a 8.12% stake. Company insiders hold 0.79%. Data sourced from SEC Form 13F as of March 31, 2025.