Darwin Global Management, Ltd.
· Reduced
−$635M
Change
−4.1M
Date
Q1 2026
IN
13F filing season in progress; institutional ownership uses the last closed quarter (2026 Q1)
| Investor | Type | Est. change | Change | Δ Own | Date | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Darwin Global Management, Ltd.
· Reduced
−$635M
Change
−4.1M
Date
Q1 2026
|
Darwin Global Management, Ltd. | Reduced· Q1 2026 | −$635M | −4.1M | – | Q1 2026 | |||||
|
FMR LLC
· Added
+$497M
Change
+3.2M
Δ Own
+32.6%
Date
Q1 2026
|
FMR LLC | Added· Q1 2026 | +$497M | +3.2M | +32.6% | Q1 2026 | |||||
|
Norges
· Exited
−$448M
Change
−2.9M
Δ Own
−100.0%
Date
Q1 2026
|
Norges | Exited· Q1 2026 | −$448M | −2.9M | −100.0% | Q1 2026 | |||||
|
Orbis Allan Gray Ltd
· Reduced
−$355M
Change
−2.3M
Date
Q1 2026
|
Orbis Allan Gray Ltd | Reduced· Q1 2026 | −$355M | −2.3M | – | Q1 2026 | |||||
|
Artisan Partners Limited Partnership
· Added
+$259M
Change
+1.7M
Date
Q1 2026
|
Artisan Partners Limited Partnership | Added· Q1 2026 | +$259M | +1.7M | – | Q1 2026 | |||||
|
BlackRock
· Added
+$248M
Change
+1.6M
Date
Q1 2026
|
BlackRock | Added· Q1 2026 | +$248M | +1.6M | – | Q1 2026 | |||||
|
Capital World Investors
· New
+$209M
Change
+1.4M
Date
Q1 2026
|
Capital World Investors | New· Q1 2026 | +$209M | +1.4M | – | Q1 2026 | |||||
|
D. E. Shaw & Co., Inc.
· Added
+$196M
Change
+1.3M
Δ Own
+29.3%
Date
Q1 2026
|
D. E. Shaw & Co., Inc. | Added· Q1 2026 | +$196M | +1.3M | +29.3% | Q1 2026 | |||||
|
Paradigm Biocapital Advisors LP
· New
+$193M
Change
+1.3M
Date
Q1 2026
|
Paradigm Biocapital Advisors LP | New· Q1 2026 | +$193M | +1.3M | – | Q1 2026 | |||||
|
Ameriprise Financial Inc
· Added
+$167M
Change
+1.1M
Date
Q1 2026
|
Ameriprise Financial Inc | Added· Q1 2026 | +$167M | +1.1M | – | Q1 2026 | |||||
|
Westfield Capital Management Co LP
· Added
+$159M
Change
+1.0M
Date
Q1 2026
|
Westfield Capital Management Co LP | Added· Q1 2026 | +$159M | +1.0M | – | Q1 2026 | |||||
|
Citadel Advisors LLC
· Added
+$158M
Change
+1.0M
Δ Own
+88.6%
Date
Q1 2026
|
Citadel Advisors LLC | Added· Q1 2026 | +$158M | +1.0M | +88.6% | Q1 2026 | |||||
|
JPMorgan Chase & Co
· Added
+$146M
Change
+951K
Date
Q1 2026
|
JPMorgan Chase & Co | Added· Q1 2026 | +$146M | +951K | – | Q1 2026 | |||||
|
T. Rowe Price Associates
· Reduced
−$146M
Change
−947K
Date
Q1 2026
|
T. Rowe Price Associates | Reduced· Q1 2026 | −$146M | −947K | – | Q1 2026 | |||||
|
Jefferies Financial Group Inc.
· Reduced
−$142M
Change
−923K
Date
Q1 2026
|
Jefferies Financial Group Inc. | Reduced· Q1 2026 | −$142M | −923K | – | Q1 2026 | |||||
| Insider | Title | Type | Price | Qty | Value | Owned | ΔOwn | Trade date | Filed date | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Lewis William
· Director
2 operations
−$1.1M
Price
$105.62–$106.43
Qty
−11K
Owned
259K
ΔOwn
−4.0%
Trade date
Jul 23, 2026
Filed date
Jul 24, 2026
|
Lewis William | Director | 2 operations | $105.62–$106.43 | −11K | −$1.1M | 259K | −4.0% | Jul 23, 2026 | Jul 24, 2026 | |||||||||
|
Lewis William
· Director
4 operations
0
|
Lewis William | Director | 4 operations | $17.16–$30.46 | 0 | – | 0 | – | Jul 23, 2026 | Jul 24, 2026 | |||||||||
|
Lewis William
· Director
3 operations
−$1.3M
|
Lewis William | Director | 3 operations | $116.55–$118.52 | −11K | −$1.3M | 259K | −4.0% | Jul 9, 2026 | Jul 10, 2026 | |||||||||
|
Lewis William
· Director
4 operations
0
|
Lewis William | Director | 4 operations | $17.16–$30.46 | 0 | – | 4K | – | Jul 9, 2026 | Jul 10, 2026 | |||||||||
|
Flammer Martina M.d.
· Officer
2 operations
−$1.4M
|
Flammer Martina M.d. | Officer | 2 operations | $109.02–$110.60 | −12K | −$1.4M | 60K | −16.9% | Jul 6, 2026 | Jul 8, 2026 | |||||||||
|
Flammer Martina M.d.
· Officer
4 operations
0
|
Flammer Martina M.d. | Officer | 4 operations | $19.74–$29.13 | 0 | – | 4K | – | Jul 6, 2026 | Jul 8, 2026 | |||||||||
|
Lewis William
· Director
5 operations
−$2.2M
Price
$102.34–$106.27
Qty
−21K
Owned
259K
ΔOwn
−7.6%
Trade date
Jun 25, 2026
Filed date
Jun 26, 2026
|
Lewis William | Director | 5 operations | $102.34–$106.27 | −21K | −$2.2M | 259K | −7.6% | Jun 25, 2026 | Jun 26, 2026 | |||||||||
|
Lewis William
· Director
4 operations
0
|
Lewis William | Director | 4 operations | $17.16–$30.46 | 0 | – | 9K | – | Jun 25, 2026 | Jun 26, 2026 | |||||||||
|
Butera Samuele
· Officer
2 operations
20K
|
Butera Samuele | Officer | 2 operations | – | 20K | – | 13K | – | Jun 23, 2026 | Jun 24, 2026 | |||||||||
|
Smith Michael Alexander
· Officer
Sell
−$173K
|
Smith Michael Alexander | Officer | Sell | $95.82 | −2K | −$173K | 38K | −4.6% | Jun 22, 2026 | Jun 24, 2026 | |||||||||
|
Lewis William
· Director
Sell
−$613K
|
Lewis William | Director | Sell | $94.03 | −7K | −$613K | 259K | – | Jun 8, 2026 | Jun 10, 2026 | |||||||||
|
Flammer Martina M.d.
· Officer
Sell
−$193K
|
Flammer Martina M.d. | Officer | Sell | $103.78 | −2K | −$193K | 60K | – | Jun 5, 2026 | Jun 5, 2026 | |||||||||
|
Adsett Roger
· Officer
Sell
−$242K
|
Adsett Roger | Officer | Sell | $102.27 | −2K | −$242K | 99K | – | Jun 3, 2026 | Jun 5, 2026 | |||||||||
|
Bonstein Sara
· CFO
Sell
−$246K
|
Bonstein Sara | CFO | Sell | $102.27 | −2K | −$246K | 69K | – | Jun 3, 2026 | Jun 5, 2026 | |||||||||
|
Smith Michael Alexander
· Officer
Sell
−$221K
|
Smith Michael Alexander | Officer | Sell | $102.27 | −2K | −$221K | 39K | – | Jun 3, 2026 | Jun 5, 2026 | |||||||||
N
A
M
A
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G
675 reporting institutions disclosed INSM position changes in the Q1 2026 snapshot. The largest disclosed owners include JPMorgan Chase & Co, Darwin Global Management, Ltd., FMR LLC. WhoBought does not publish a total institutional-ownership percentage for INSM: aggregate 13F filings can report the same shares more than once (a parent manager and its subsidiary filers, or shares out on loan), so a summed percentage would overstate what institutions really hold.
For each manager, WhoBought compares accepted consecutive 13F share counts. Share change is current shares minus prior shares. Estimated dollar change is that signed share change multiplied by the split-adjusted quarter-mean close. The activity table on this page uses Q1 2026.
An investor crossing 5% of a share class generally files Schedule 13D for activist intent or Schedule 13G for a passive position. The technical form names appear here rather than in the activity rows.
Ownership and institutional activity come from SEC Form 13F filings. Insider activity comes from SEC Form 4, and large-shareholder activity from SEC Schedules 13D and 13G. FMP supplies price data only. Company logos use the local verified Parqet cache with one shared fallback.
Form 13F is a quarterly disclosure and is normally filed after the quarter ends. Every ownership and activity value therefore names its represented period; it is not presented as a live position.
A muted dash marks a missing table value. It means the filing omitted the value, comparable data is unavailable, or no prior position exists for comparison.