Insmed Incorporated (INSM) Ownership
INSM ownership summary
as of October 18, 2026- Institutions
- 105.5% of shares outstanding
- Insiders
- 0.51% of shares outstanding
- Shares outstanding
- 218.4M
- Float
- 216.9M shares available to trade
- Short interest
- 7.12% 13.8M shares short
- Days to cover
- 6.46 short interest up 27.8% vs prior month
- Institutions 105.49%
- Insiders 0.51%
INSM top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | FMR Inc | 7.39% | 16.1M | $1.55B | +3.0M (+22.7%) | June 30, 2026 |
| 2 | BlackRock Inc | 7.24% | 15.8M | $1.52B | −870,162 (−5.2%) | June 30, 2026 |
| 3 | JPMorgan Chase & Co | 4.78% | 10.4M | $1.00B | −13.7M (−56.8%) | June 30, 2026 |
| 4 | Vanguard Portfolio Management, LLC | 4.77% | 10.4M | $1.00B | +36,160 (+0.3%) | June 30, 2026 |
| 5 | Vanguard Capital Management, LLC | 4.48% | 9.8M | $942.6M | +148,734 (+1.5%) | June 30, 2026 |
| 6 | Baker Bros Advisors LP | 4.03% | 8.8M | $846.8M | +1.4M (+18.5%) | June 30, 2026 |
| 7 | Capital Research & Mgmt Co - Division 3 | 3.77% | 8.2M | $793.1M | +2.6M (+47.2%) | June 30, 2026 |
| 8 | Darwin Global Management, Ltd. | 2.94% | 6.4M | $619.1M | −10.4M (−61.7%) | June 30, 2026 |
| 9 | Ameriprise Financial Inc | 2.83% | 6.2M | $594.9M | +3.1M (+102.1%) | June 30, 2026 |
| 10 | Orbis Allan Gray Ltd | 2.78% | 6.1M | $585.0M | +4.2M (+224.5%) | June 30, 2026 |
| 11 | State Street Corp | 2.77% | 6.1M | $582.6M | +500,475 (+9.0%) | June 30, 2026 |
| 12 | D. E. Shaw & Co LP | 2.69% | 5.9M | $565.9M | +252,134 (+4.5%) | June 30, 2026 |
| 13 | Artisan Partners Limited Partnership | 2.49% | 5.4M | $523.9M | −1.1M (−16.6%) | June 30, 2026 |
| 14 | RTW INVESTMENTS, LLC | 2.22% | 4.8M | $466.2M | — | June 30, 2026 |
| 15 | Geode Capital Management, LLC | 1.93% | 4.2M | $406.3M | −230,234 (−5.2%) | June 30, 2026 |
| 16 | T. Rowe Price Associates, Inc. | 1.56% | 3.4M | $327.8M | +312,483 (+10.1%) | June 30, 2026 |
| 17 | NORGES BANK | 1.55% | 3.4M | $325.2M | +466,670 (+16.0%) | June 30, 2026 |
| 18 | Jupiter Topco LLC | 1.19% | 2.6M | $250.8M | +2.6M (0.0%) | June 30, 2026 |
| 19 | UBS Group AG | 1.18% | 2.6M | $248.8M | +846,965 (+48.7%) | June 30, 2026 |
| 20 | Citadel Advisors Llc | 1.17% | 2.6M | $246.2M | +374,402 (+17.2%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 14 holders added 19.9M shares and 5 cut 26.3M.
INSM top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 3.16% | 6.9M | $663.5M | −14,337 (−0.2%) | August 31, 2026 |
| 2 | American Funds Growth Fd of Amer A | 3.09% | 6.8M | $649.9M | +495,942 (+7.9%) | September 30, 2026 |
| 3 | Vanguard Small Cap Index | 1.13% | 2.5M | $236.6M | −35,986 (−1.4%) | September 30, 2026 |
| 4 | Vanguard MStar Mid Cap Index Instl | 1.07% | 2.3M | $225.1M | −6,098 (−0.3%) | September 30, 2026 |
| 5 | Vanguard MStar Growth Index Investor | 0.88% | 1.9M | $185.9M | +142,689 (+8.0%) | September 30, 2026 |
| 6 | iShares Biotechnology ETF | 0.77% | 1.7M | $161.6M | −12,712 (−0.8%) | September 30, 2026 |
| 7 | Fidelity Advisor Growth Opps M | 0.76% | 1.7M | $159.2M | — | August 31, 2026 |
| 8 | JPMorgan Mid Cap Growth I | 0.71% | 1.5M | $148.4M | +113,457 (+7.9%) | August 31, 2026 |
| 9 | JPMorgan Growth Advantage A | 0.69% | 1.5M | $144.1M | +143,497 (+10.6%) | August 31, 2026 |
| 10 | Polar Capital Biotech S Inc | 0.66% | 1.4M | $139.5M | +280,768 (+24.0%) | August 31, 2026 |
| 11 | JPMorgan Large Cap Growth I | 0.66% | 1.4M | $139.0M | −676,128 (−31.9%) | August 31, 2026 |
| 12 | Orbis Global Equity Investor | 0.66% | 1.4M | $138.7M | +1.0M (+249.6%) | June 30, 2026 |
| 13 | Vanguard MStar Small Cap Growth Indx Inv | 0.63% | 1.4M | $131.6M | −64,304 (−4.5%) | September 30, 2026 |
| 14 | Fidelity Select Biotechnology | 0.57% | 1.2M | $119.7M | +900 (+0.1%) | August 31, 2026 |
| 15 | iShares Russell Mid-Cap Growth ETF | 0.55% | 1.2M | $116.2M | −1,290 (−0.1%) | September 30, 2026 |
| 16 | Strategic Advisers Fidelity US TtlStk | 0.54% | 1.2M | $113.9M | −475,989 (−28.7%) | August 31, 2026 |
| 17 | State Street® SPDR® S&P® Biotech ETF | 0.53% | 1.2M | $111.2M | −22,000 (−1.9%) | September 30, 2026 |
| 18 | American Funds IS® Growth 1 | 0.49% | 1.1M | $102.0M | +25,428 (+2.5%) | September 30, 2026 |
| 19 | Fidelity Extended Market Index | 0.48% | 1.1M | $101.7M | −10,874 (−1.0%) | August 31, 2026 |
| 20 | Pictet-Biotech P USD | 0.47% | 1.0M | $99.0M | +45,258 (+4.6%) | September 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
INSM insider transactions
latest 20| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-04-16 | William Lewis | Sell | $143.97 | 10,699 | $1.5M |
| 2026-04-06 | William Lewis | Sell | $163.22 | 10,699 | $1.7M |
| 2026-04-01 | Roger Adsett | Sell | $164.63 | 88,060 | $14.5M |
| 2026-03-30 | Michael Alexander Smith | Sell | $150.98 | 19,638 | $3.0M |
| 2026-03-19 | William Lewis | Sell | $143.52 | 10,699 | $1.5M |
| 2026-03-05 | William Lewis | Sell | $146.03 | 10,699 | $1.6M |
| 2026-02-19 | William Lewis | Sell | $150.97 | 10,699 | $1.6M |
| 2026-02-09 | William Lewis | Sell | $147.79 | 13,396 | $2.0M |
| 2026-02-03 | Sara Bonstein | Sell | $156.34 | 748 | $116,942 |
| 2026-02-03 | William Lewis | Sell | $156.34 | 3,009 | $470,427 |
| 2026-02-03 | Roger Adsett | Sell | $156.17 | 791 | $123,530 |
| 2026-02-03 | Michael Alexander Smith | Sell | $156.27 | 640 | $100,013 |
| 2026-01-20 | William Lewis | Sell | $158.93 | 10,699 | $1.7M |
| 2026-01-12 | William Lewis | Sell | $169.00 | 19,215 | $3.2M |
| 2026-01-08 | Michael Alexander Smith | Sell | $174.17 | 1,053 | $183,401 |
| 2026-01-08 | Roger Adsett | Sell | $174.17 | 2,059 | $358,616 |
| 2026-01-08 | Sara Bonstein | Sell | $174.17 | 1,447 | $252,024 |
| 2026-01-08 | William Lewis | Sell | $174.17 | 3,223 | $561,350 |
| 2026-01-07 | Michael Alexander Smith | Sell | $175.07 | 709 | $124,125 |
| 2026-01-07 | Roger Adsett | Sell | $175.07 | 802 | $140,406 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
INSM shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns INSM
Institutional investors own 105.5% of Insmed's shares and insiders 0.51%. The largest holder is FMR Inc with 7.39% of the shares (16.1M), as of June 30, 2026. Among the top 20 institutions, 14 added shares and 5 reduced their stake in the latest filings. Short interest is 7.12% of the float, or 6.46 days of average trading volume. The share count rose 330.2% since 2014.
Related: INSM analyst forecast, INSM key metrics. See the INSM stock overview for the latest quote and news.
INSM ownership FAQ
Who owns the most Insmed stock?
The largest shareholders of Insmed are FMR Inc (7.39%), BlackRock Inc (7.24%), JPMorgan Chase & Co (4.78%), Vanguard Portfolio Management, LLC (4.77%), Vanguard Capital Management, LLC (4.48%).
What percentage of Insmed is owned by institutions?
Institutions hold 105.5% of Insmed's shares outstanding; insiders hold 0.51%.
Which funds own Insmed?
The largest fund holders of Insmed are Vanguard MStar Total Stk Mkt Idx Invest (3.16%), American Funds Growth Fd of Amer A (3.09%), Vanguard Small Cap Index (1.13%), Vanguard MStar Mid Cap Index Instl (1.07%), Vanguard MStar Growth Index Investor (0.88%).
What is Insmed's short interest?
13.8M shares of Insmed were sold short, 7.12% of the float; at the average daily volume it would take 6.46 days to cover.
Are insiders buying or selling Insmed?
Of the latest 20 reported insider transactions in Insmed (since January 7, 2026), 0 were purchases and 20 were sales.
How many shares of Insmed are outstanding?
Insmed has 218.4M shares outstanding, of which 216.9M are in the public float.