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 Sep 30, 2025
Ownership Breakdown
177
Institutional Holders
▲ 43 vs Q2
$1.49B
Total Inst. Value
▲ $967.49M vs Q2
83.13M
Shares Outstanding
freeFloat 66.48%
109.72M
13F Shares Held
▲ 28.03M 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
AMLX largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
FMR LLC pharmaceutical preparations | 11.38M | 12.77% | 12.77% | $154.64B | Nov 13, 2025 | ▲ 8.33M |
PERCEPTIVE ADVISORS LLC pharmaceutical preparations | 8.95M | 10.04% | 10.04% | $121.66B | Nov 14, 2025 | ▲ 1.05M |
BLACKROCK, INC. pharmaceutical preparations | 7.14M | 8.01% | 8.01% | $97.04B | Nov 12, 2025 | ▲ 1.63M |
ADAGE CAPITAL PARTNERS GP, L.L.C. pharmaceutical preparations | 6.82M | 7.65% | 7.65% | $92.64B | Nov 14, 2025 | ▼ 1.98M |
TCG CROSSOVER MANAGEMENT, LLC pharmaceutical preparations | 6.24M | 7.00% | 7.00% | $84.85B | Nov 17, 2025 | ▲ 300.0K |
VANGUARD GROUP INC pharmaceutical preparations | 5.27M | 5.92% | 5.92% | $71.67B | Nov 7, 2025 | ▲ 775.7K |
SATURN V CAPITAL MANAGEMENT LLC pharmaceutical preparations | 4.60M | 5.17% | 5.17% | $62.58B | Nov 14, 2025 | ▲ 1.34M |
COMMODORE CAPITAL LP pharmaceutical preparations | 4.08M | 4.57% | 4.57% | $55.39B | Nov 14, 2025 | NEW |
FIRST LIGHT ASSET MANAGEMENT, LLC pharmaceutical preparations | 3.36M | 3.76% | 3.76% | $45.61B | Nov 14, 2025 | NEW |
POINT72 ASSET MANAGEMENT, L.P. pharmaceutical preparations | 2.79M | 3.13% | 3.13% | $37.92B | Nov 14, 2025 | ▼ 1.75M |
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
21
Increased
+21.06M shares13
New Positions
first time holders14
Decreased
−9.18M shares0
Sold Out
fully exitedNet shares change (top 50)
+11.88M
+21.06M / −9.18M
Net new holders
+20
13 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 100.0% 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 FMR LLC, holding approximately 11.38 million shares — equal to 12.77% of outstanding shares — as of September 30, 2025.
A total of 177 institutional investors currently hold AMLX stock, with a combined institutional value of approximately $1.49 billion 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 100.0% of shares. The largest shareholder is FMR LLC with a 12.77% stake. Company insiders hold 33.52%. Data sourced from SEC Form 13F as of September 30, 2025.