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INSM · INSMED Inc · Holdings

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$95.67 +0.38 (+0.40%)
Market Cap
$20.81B
Shares
218.38M
Volume · Oct 20 2.6M Avg daily vol (3M) 2.61M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Institutional holdings are being reconciled with SEC filings. Holder totals and changes may be incomplete until reconciliation finishes.
The Sep 30, 2026 filing window is still open — showing the latest known positions. Funds that have not filed yet carry their prior-quarter positions; a fund that filed without this stock counts as sold out. Each fund's Change is measured against its own previous reported quarter, shown in the Reported column. Pick a completed quarter in the Quarter selector below to put every fund on one quarter and see the stock-wide activity breakdown.
Holders: 679
Total Value: $24,868,087,836
Total Shares: 233,141,230
Showing 1–100 of 725 holdings by value · page 1 of 8

Institutional Ownership Trend

27 quarters

Holder Concentration

Across 671 13F filers
Top Holder
7.0%
Sep 2023 → Jun 2026 · range 7.0% – 10.9%
of institutional value
Top 5
27.0%
Sep 2023 → Jun 2026 · range 27.0% – 40.6%
of institutional value
Top 10
42.4%
Sep 2023 → Jun 2026 · range 40.1% – 53.4%
of institutional value
HHI
255
Sep 2023 → Jun 2026 · range 255 – 420
Broadly held

Who Holds INSM

Last 8 quarters through Sep 30, 2026 (filing window open)

Each kind of 13F filer's share of the common shares 13F filers report. Holder type comes from regulatory records, never the filer's name; style, turnover and horizon are measured from each filer's own 13F book. The quarter selector does not change this card.

Jun 30, 2026, the newest closed quarter: 668 filers, like-for-like change +0.6%; actively managed books +0.9%; index-like books -0.5%.

Holder type Share Filers Change
Registered adviser 40.0% 337 +13.8%
Exempt adviser 4.0% 10 -48.5%
Adviser 8.6% 18 0.0%
Bank 11.0% 27 -35.6%
Insurer 0.5% 4 -6.1%
Broker-dealer 0.1% 3 +7.8%
Benefit plan 0.3% 7 -3.1%
Non-US 3.8% 16 +29.4%
Holding company 16.4% 13 +7.2%
Unknown 15.4% 233 +34.5%

The Sep 30, 2026 filing window is still open, so its bar carries the Jun 30, 2026 positions of filers that have not filed yet.

How the mix is measured

Shares are 13F common shares restated to today's split basis; options and principal amounts are left out. The change compares only filers with a 13F in both quarters and keeps each filer in its bucket of the later quarter on both sides; a filer that continues under a new CIK is compared through its successor. Holder type comes from each filer's current regulatory profile; client base and private funds come from the Form ADV roster current at each quarter end (rosters from December 2019, so an earlier quarter reads Unknown). Style, turnover, horizon and book size are measured from each filer's 13F book in the newest measured quarter, and Not measured means none was. Actively managed books are those measured systematic-like, concentrated or diversified active.

Excluded 7 holders with no observed 2026-03-31 13F and 5 holders with no observed 2026-06-30 13F. Compared across CIK changes: JANUS HENDERSON GROUP PLC continues as Jupiter Topco LLC.

Conviction and Crowding

668 13F filers, quarter ended Jun 30, 2026

Measured across every 13F filer's common-share book once the quarter's filing window closed. Crowding counts filers with high turnover or that advise private funds on Form ADV.

Conviction holders
16
2.40% of filers hold it in their top 10
Mar 31, 2026: 27
Holders above 5%
8
median weight 0.015%
Mar 31, 2026: 12
Crowding
—
holders exceed shares outstanding: 13F filers report more shares than the cover-page count, which predates an issuance, is misstated, or misses shares lent and reported twice
Private-fund advisers
—
of shares outstanding
Institutional ownership
—
holders exceed shares outstanding: 13F filers report more shares than the cover-page count, which predates an issuance, is misstated, or misses shares lent and reported twice
Top 10 holders
43.9%
of 13F shares, Herfindahl 0.027
Active holders
+0.9%
like-for-like share change of active filers
5% stakes on record
6
0 13D, 6 13G (5 institutional, 0 passive, 0 exempt)
How long holders have held it value-weighted 15.0 quarters
Under 1 year 20.0% 1 to 3 years 29.4% 3 years or more 50.6% Since coverage start 0.000%

Managers in the top fifth by current three-year FundScore alpha were net sellers of $19,071,420 (0 buying, 1 selling).

Estimated Holder Cost Basis

Quarter ended Jun 30, 2026, on that quarter's share basis

Estimated, never filed: each 13F buy is costed at its quarter's average traded price and each sale keeps the average cost, so this is what holders paid on average if they traded evenly through each quarter.

Estimated avg cost
$101.72
estimated per share
Mar 31, 2026: $93.09
Quarter-end price
$106.60
implied by 13F values
Estimated gain or loss
+4.8%
price against the estimated cost
Estimated at a loss
46.8%
of costed 13F value

Estimated cost covers 38.8% of the 13F shares; positions already held when a filer's 13F history starts, or bought in a quarter without a trusted average price, have no estimate.

Shared Holders

Companies INSM's active holders also own, quarter ended Jun 30, 2026
# Company Shared holders
1 ELVN Enliven Therapeutics, Inc. 24
2 XENE Xenon Pharmaceuticals Inc. 23
3 PCVX Vaxcyte, Inc. 20
4 NAMS NewAmsterdam Pharma Co N.V. 17
5 RVMD Revolution Medicines, Inc. 34
6 COGT Cogent Biosciences, Inc. 22
7 BBIO BridgeBio Pharma, Inc. 22
8 VERA Vera Therapeutics, Inc. 17
9 CYTK Cytokinetics Inc 25
10 RARE Ultragenyx Pharmaceutical Inc. 16

Shareholder Targets

13F filers that own its peers but not INSM, quarter ended Jun 30, 2026

Found through its holder-overlap peers: ELVN, XENE, PCVX, NAMS, RVMD, COGT, BBIO, VERA, CYTK, RARE, RYTM, CLDX, PRAX, SYRE, ASND, PTGX, MDGL, ALKS, CRNX, BLTE. 696 filers in all.

# Filer In peers
1 RA CAPITAL MANAGEMENT, L.P. Registered adviser, Concentrated $4,480,297,262 4 held
2 FARALLON CAPITAL MANAGEMENT LLC Registered adviser, Diversified active $4,453,215,250 5 held
3 Avoro Capital Advisors LLC Registered adviser, Concentrated $3,798,134,406 6 held
4 PERCEPTIVE ADVISORS LLC Registered adviser, Diversified active $1,886,510,132 7 held
5 Capital World Investors Adviser, Diversified active $1,710,263,472 7 held
6 DEERFIELD MANAGEMENT COMPANY, L.P. Registered adviser, Diversified active $1,431,326,244 7 held
7 Nextech Invest, Ltd. Exempt adviser, Concentrated $1,423,531,573 1 held
8 Driehaus Capital Management LLC Registered adviser, Diversified active $1,361,128,398 11 held
9 MASSACHUSETTS FINANCIAL SERVICES CO /MA/ Registered adviser, Diversified active $1,008,475,430 6 held
10 Kohlberg Kravis Roberts & Co. L.P. Registered adviser, Concentrated $987,677,120 1 held

Fund Ownership of INSM by Fund Type

Registered funds' Form N-PORT reports for the quarter ended Jun 30, 2026

Index funds and index ETFs hold 15.97% of shares outstanding.

Fund type Of shares outstanding Shares
Index funds 2.53% 5,530,160
Index ETFs 13.44% 29,342,548
Active ETFs 0.51% 1,107,078
Active funds 18.44% 40,267,149
Unclassified 3.43% 7,484,427
All registered funds 38.34% 83,731,362
How fund types are measured

Each fund series counts once, with its latest Form N-PORT report dated inside the quarter; only long share positions count, restated to today's split basis. The fund type is the series' latest Form N-CEN answer on or before the quarter end (the index-fund box and the exchange-traded flag), never its name. Unclassified funds have no usable N-CEN; unit investment trusts are among them, so index ownership is a floor. Funds sit inside their advisers' 13F reports, so these shares overlap the 13F figures and are never added to them.

Showing 100 of 725
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Holder Value (USD) % of 13F Shares Open

Showing the top 100 of 725 holders. Create a free account to see every holder, past quarters, search, filters and CSV export.

Key facts CIK 1104506 CUSIP 457669307 13F (30d) 87 filings 82 filers Visit website Investor relations