Amylyx Pharmaceuticals, Inc.
Amylyx Pharmaceuticals, Inc. (AMLX) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · AMLX · as of Mar 31, 2025
Ownership Breakdown
140
Institutional Holders
▲ 6 vs Q4
$261.60M
Total Inst. Value
▲ $73.32M vs Q4
83.13M
Shares Outstanding
freeFloat 66.48%
73.90M
13F Shares Held
▲ 24.09M 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
AMLX largest shareholders · institutional ownership
Q1 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
PERCEPTIVE ADVISORS LLC pharmaceutical preparations | 7.87M | 9.19% | 9.19% | $27.88B | Aug 6, 2025 | ▲ 1.10M |
TCG CROSSOVER MANAGEMENT, LLC pharmaceutical preparations | 5.94M | 6.94% | 6.94% | $21.04B | May 14, 2025 | ▲ 1.30M |
ADAGE CAPITAL PARTNERS GP, L.L.C. pharmaceutical preparations | 5.70M | 6.65% | 6.65% | $20.17B | May 15, 2025 | NEW |
VANGUARD GROUP INC pharmaceutical preparations | 4.12M | 4.80% | 4.80% | $14.57B | May 9, 2025 | ▲ 1.42M |
MILLENNIUM MANAGEMENT LLC pharmaceutical preparations | 3.08M | 3.60% | 3.60% | $10.91B | May 15, 2025 | ▲ 2.49M |
NANTAHALA CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 2.93M | 3.42% | 3.42% | $10.39B | May 15, 2025 | ▲ 1.48M |
CITADEL ADVISORS LLC pharmaceutical preparations | 2.76M | 3.22% | 3.22% | $9.76B | May 15, 2025 | ▲ 787.1K |
ABRDN PLC pharmaceutical preparations | 2.43M | 2.84% | 2.84% | $8.60B | May 13, 2025 | ▲ 707.6K |
SATURN V CAPITAL MANAGEMENT LLC pharmaceutical preparations | 2.43M | 2.83% | 2.83% | $8.59B | May 15, 2025 | ▲ 1.54M |
683 CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 2.41M | 2.81% | 2.81% | $8.54B | May 15, 2025 | ▲ 481.4K |
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
32
Increased
+17.27M shares6
New Positions
first time holders9
Decreased
−3.03M shares0
Sold Out
fully exitedNet shares change (top 50)
+14.25M
+17.27M / −3.03M
Net new holders
+29
6 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
AMLX insider trading · insider activity
Source: SEC Form 4
Insiders have been primarily selling shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
4
Buy transactions
22
Sell transactions
0.18
Buy/Sell ratio
$1M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
Firestone Karen director | May 21, 2026 | Purchase | 3,800 | $13.51 | $51.3K | 66.9K | Form 4 ↗ |
Cohen Joshua B Co-Chief Executive Officer | Mar 5, 2026 | Award | 248,865 | — | — | 3.58M | Form 4 ↗ |
Cohen Joshua B Co-Chief Executive Officer | Mar 5, 2026 | Award | 373,295 | $14.10 | $5.26M | 373.3K | Form 4 ↗ |
Mazzariello Gina Chief Legal Officer | Mar 5, 2026 | Award | 74,660 | — | — | 209.1K | Form 4 ↗ |
Mazzariello Gina Chief Legal Officer | Mar 5, 2026 | Award | 111,990 | $14.10 | $1.58M | 112.0K | Form 4 ↗ |
FRATES JAMES M Chief Financial Officer | Mar 5, 2026 | Award | 95,990 | — | — | 261.6K | Form 4 ↗ |
FRATES JAMES M Chief Financial Officer | Mar 5, 2026 | Award | 143,985 | $14.10 | $2.03M | 144.0K | Form 4 ↗ |
Klee Justin B. Co-Chief Executive Officer | Mar 5, 2026 | Award | 248,865 | — | — | 3.58M | Form 4 ↗ |
Klee Justin B. Co-Chief Executive Officer | Mar 5, 2026 | Award | 373,295 | $14.10 | $5.26M | 373.3K | Form 4 ↗ |
Bedrosian Camille L Chief Medical Officer | Mar 5, 2026 | Award | 95,990 | — | — | 265.3K | 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
Amylyx Pharmaceuticals, Inc. (AMLX) is primarily owned by institutional investors, who hold approximately 88.9% of total shares outstanding. Company insiders own approximately 33.52%, while retail and public investors account for the remaining 0.00%.
The largest institutional shareholder of Amylyx Pharmaceuticals, Inc. is PERCEPTIVE ADVISORS LLC, holding approximately 7.87 million shares — equal to 9.19% of outstanding shares — as of March 31, 2025.
A total of 140 institutional investors currently hold AMLX stock, with a combined institutional value of approximately $261,601,266 as of the most recent 13F filing period.
Frequently asked questions
AMLX ownershipAmylyx Pharmaceuticals, Inc. (AMLX) is primarily owned by institutional investors, who hold approximately 88.9% of shares. The largest shareholder is PERCEPTIVE ADVISORS LLC with a 9.19% stake. Company insiders hold 33.52%. Data sourced from SEC Form 13F as of March 31, 2025.