Insmed Incorporated (INSM) Shareholders & Insider Trades
Insmed shareholders at a glance
The largest holder of Insmed stock is Fidelity Management & Research Co. LLC, with 16.1 million shares (7.39% of the company), worth about $1.97 billion as of September 25, 2026. The 10 largest holders together own 43.8%.
In Q2 2026, 725 institutional holdings reports listed shares worth $24.20 billion.
Insiders reported 100 transactions in the last two years: 57 sales worth $167.01 million and no purchases. The newest one on file is from May 14, 2026 (Flammer Martina, Officer).
Major holders as of September 25, 2026; quarterly totals from institutional holdings reports (latest Q2 2026); insider transactions on file through May 14, 2026.
Insmed Incorporated
Shareholders Summary
2026Q2
Ownership by Type
Geographic Distribution
Largest Insmed shareholders
| Holder | Shares | % of company | Value |
|---|---|---|---|
| Fidelity Management & Research Co. LLC | 16.1 million | 7.39% | $2.0B |
| BlackRock Advisors LLC | 13.1 million | 5.99% | $1.6B |
| JPMorgan Investment Management, Inc. | 10.4 million | 4.78% | $1.3B |
| Vanguard Portfolio Management LLC | 10.4 million | 4.77% | $1.3B |
| Vanguard Capital Management LLC | 9.8 million | 4.48% | $1.2B |
| Baker Bros. Advisors LP | 8.8 million | 4.03% | $1.1B |
| Capital Research & Management Co. (International Investors) | 8.2 million | 3.77% | $1.0B |
| Darwin Global Management Ltd. | 6.4 million | 2.94% | $783.0M |
| Ameriprise Trust Co. | 6.2 million | 2.83% | $753.0M |
| Orbis Investment Management Ltd. | 6.1 million | 2.78% | $740.0M |
As of September 25, 2026.
Insmed institutional holdings by quarter
| Quarter | Reports | Shares | Value |
|---|---|---|---|
| Q2 2026 | 725 | – | $24.2B |
| Q1 2026 | 719 | 222.0 million | $35.9B |
| Q4 2025 | 743 | 219.0 million | $38.0B |
| Q3 2025 | 633 | – | $33.9B |
| Q2 2025 | 573 | 215.0 million | $21.6B |
| Q1 2025 | 478 | 201.0 million | $15.4B |
| Q4 2024 | 492 | 193.0 million | $13.3B |
| Q3 2024 | 467 | 192.0 million | $14.0B |
Shares and value held by institutions that file quarterly holdings reports (options not included).
Insmed insider trades
| Insider | Date | Title | Transaction | Value |
|---|---|---|---|---|
| Flammer Martina | May 14, 2026 | Officer | Sale at price 112.76 - 117.54 per share. | $2.1M |
| Lewis William H | May 13, 2026 | Chief Executive Officer | Sale at price 116.18 per share. | $1.5M |
| Bonstein Sara M | May 13, 2026 | Chief Financial Officer | Sale at price 116.18 per share. | $961,041 |
| Adsett Roger | May 13, 2026 | Chief Operating Officer | Sale at price 116.18 per share. | $678,143 |
| Smith Michael Alexander | May 13, 2026 | Officer | Sale at price 116.18 per share. | $477,384 |
| Anderson Elizabeth M | May 13, 2026 | Director | Stock Award(Grant) at price 0.00 per share. | – |
| Sharoky Melvin A | May 13, 2026 | Director | Stock Award(Grant) at price 0.00 per share. | – |
| Schafer Carol Anne | May 13, 2026 | Director | Stock Award(Grant) at price 0.00 per share. | – |
| Brennan David R | May 13, 2026 | Director | Stock Award(Grant) at price 0.00 per share. | – |
| Lee Leo Yao | May 13, 2026 | Director | Stock Award(Grant) at price 0.00 per share. | – |
| Flammer Martina | May 11, 2026 | Officer | Sale at price 100.35 - 101.18 per share. | $1.3M |
| Flammer Martina | May 11, 2026 | Officer | Conversion of Exercise of derivative security at price 17.07 per share. | $221,039 |
Newest 12 of 100 insider transactions in the last two years.
Questions and answers
Who owns the most Insmed stock?
Fidelity Management & Research Co. LLC, with 7.39% of the company (as of September 25, 2026). Next: BlackRock Advisors LLC (5.99%) and JPMorgan Investment Management, Inc. (4.78%).
How many institutions own Insmed stock?
725 institutional holdings reports listed Insmed shares in Q2 2026 worth $24.20 billion.
Are Insmed insiders buying or selling the stock?
In the last two years insiders reported 57 sales and no purchases (100 transactions in all); the newest on file is from May 14, 2026.
